And i added installer script in /var/www/html/app/code/core/Mage/Admin/sql/admin_setup/upgrade-1.6.1.1-1.6.1.2.php

    <?php
/**
 * Magento
 *
 * NOTICE OF LICENSE
 *
 * This source file is subject to the Open Software License (OSL 3.0)
 * that is bundled with this package in the file LICENSE.txt.
 * It is also available through the world-wide-web at this URL:
 * http://opensource.org/licenses/osl-3.0.php
 * If you did not receive a copy of the license and are unable to
 * obtain it through the world-wide-web, please send an email
 * to [email protected] so we can send you a copy immediately.
 *
 * DISCLAIMER
 *
 * Do not edit or add to this file if you wish to upgrade Magento to newer
 * versions in the future. If you wish to customize Magento for your
 * needs please refer to http://www.magento.com for more information.
 *
 * @category    Mage
 * @package     Mage_Admin
 * @copyright  Copyright (c) 2006-2017 X.commerce, Inc. and affiliates (http://www.magento.com)
 * @license    http://opensource.org/licenses/osl-3.0.php  Open Software License (OSL 3.0)
 */

/** @var $installer Mage_Core_Model_Resource_Setup */
$installer = $this;
$installer->startSetup();

$table = $installer->getConnection()
    ->newTable($installer->getTable('admin/permission_variable'))
    ->addColumn('variable_id', Varien_Db_Ddl_Table::TYPE_INTEGER, null, array(
        'identity'  => true,
        'unsigned'  => true,
        'nullable'  => false,
        'primary'   => true,
    ), 'Variable ID')
    ->addColumn('variable_name', Varien_Db_Ddl_Table::TYPE_VARCHAR, 255, array(
        'primary'   => true,
        'nullable'  => false,
        'default'   => "",
        ), 'Config Path')
    ->addColumn('is_allowed', Varien_Db_Ddl_Table::TYPE_BOOLEAN, null, array(
        'nullable'  => false,
        'default'   => 0,
        ), 'Mark that config can be processed by filters')
    ->addIndex($installer->getIdxName('admin/permission_variable', array('variable_name'), Varien_Db_Adapter_Interface::INDEX_TYPE_UNIQUE),
        array('variable_name'), array('type' => Varien_Db_Adapter_Interface::INDEX_TYPE_UNIQUE))
    ->setComment('System variables that can be processed via content filter');
$installer->getConnection()->createTable($table);

$installer->getConnection()->insertMultiple(
    $installer->getTable('admin/permission_variable'),
    array(
        array('variable_name' => 'trans_email/ident_support/name', 'is_allowed' => 1),
        array('variable_name' => 'trans_email/ident_support/email','is_allowed' =>  1),
        array('variable_name' => 'web/unsecure/base_url','is_allowed' =>  1),
        array('variable_name' => 'web/secure/base_url','is_allowed' =>  1),
        array('variable_name' => 'trans_email/ident_general/name','is_allowed' =>  1),
        array('variable_name' => 'trans_email/ident_general/email', 'is_allowed' => 1),
        array('variable_name' => 'trans_email/ident_sales/name','is_allowed' =>  1),
        array('variable_name' => 'trans_email/ident_sales/email','is_allowed' =>  1),
        array('variable_name' => 'trans_email/ident_custom1/name','is_allowed' =>  1),
        array('variable_name' => 'trans_email/ident_custom1/email','is_allowed' =>  1),
        array('variable_name' => 'trans_email/ident_custom2/name','is_allowed' =>  1),
        array('variable_name' => 'trans_email/ident_custom2/email','is_allowed' =>  1),
        array('variable_name' => 'general/store_information/name', 'is_allowed' => 1),
        array('variable_name' => 'general/store_information/phone','is_allowed'  => 1),
        array('variable_name' => 'general/store_information/address', 'is_allowed' => 1),
    )
);

$table = $installer->getConnection()
    ->newTable($installer->getTable('admin/permission_block'))
    ->addColumn('block_id', Varien_Db_Ddl_Table::TYPE_INTEGER, null, array(
        'identity'  => true,
        'unsigned'  => true,
        'nullable'  => false,
        'primary'   => true,
        ), 'Block ID')
    ->addColumn('block_name', Varien_Db_Ddl_Table::TYPE_VARCHAR, 255, array(
        'nullable'  => false,
        'default'   => "",
        ), 'Block Name')
    ->addColumn('is_allowed', Varien_Db_Ddl_Table::TYPE_BOOLEAN, null, array(
        'nullable'  => false,
        'default'   => 0,
        ), 'Mark that block can be processed by filters')
    ->addIndex($installer->getIdxName('admin/permission_block', array('block_name'), Varien_Db_Adapter_Interface::INDEX_TYPE_UNIQUE),
        array('block_name'), array('type' => Varien_Db_Adapter_Interface::INDEX_TYPE_UNIQUE))
    ->setComment('System blocks that can be processed via content filter');
$installer->getConnection()->createTable($table);

$installer->getConnection()->insertMultiple(
    $installer->getTable('admin/permission_block'),
    array(
        array('block_name' => 'core/template', 'is_allowed' => 1),
        array('block_name' => 'catalog/product_new', 'is_allowed' => 1),
    )
);

$installer->getConnection()->addColumn($installer->getTable('admin/user'), 'mobile', array(
    'type' => Varien_Db_Ddl_Table::TYPE_TEXT,
    'length' => 50,
    'nullable' => true,
    'default' => null
)); 
$installer->endSetup();

I added like this in /app/code/core/Mage/Adminhtml/Block/Api/User/Grid.php

    <?php
/**
 * Magento
 *
 * NOTICE OF LICENSE
 *
 * This source file is subject to the Open Software License (OSL 3.0)
 * that is bundled with this package in the file LICENSE.txt.
 * It is also available through the world-wide-web at this URL:
 * http://opensource.org/licenses/osl-3.0.php
 * If you did not receive a copy of the license and are unable to
 * obtain it through the world-wide-web, please send an email
 * to [email protected] so we can send you a copy immediately.
 *
 * DISCLAIMER
 *
 * Do not edit or add to this file if you wish to upgrade Magento to newer
 * versions in the future. If you wish to customize Magento for your
 * needs please refer to http://www.magento.com for more information.
 *
 * @category    Mage
 * @package     Mage_Adminhtml
 * @copyright  Copyright (c) 2006-2017 X.commerce, Inc. and affiliates (http://www.magento.com)
 * @license    http://opensource.org/licenses/osl-3.0.php  Open Software License (OSL 3.0)
 */

/**
 * Adminhtml permissions user grid
 *
 * @category   Mage
 * @package    Mage_Adminhtml
 * @author      Magento Core Team <[email protected]>
 */
class Mage_Adminhtml_Block_Api_User_Grid extends Mage_Adminhtml_Block_Widget_Grid
{

    public function __construct()
    {
        parent::__construct();
        $this->setId('permissionsUserGrid');
        $this->setDefaultSort('username');
        $this->setDefaultDir('asc');
        $this->setUseAjax(true);
    }

    protected function _prepareCollection()
    {
        $collection = Mage::getResourceModel('api/user_collection');
        $this->setCollection($collection);
        return parent::_prepareCollection();
    }

    protected function _prepareColumns()
    {
        $this->addColumn('user_id', array(
            'header'    => Mage::helper('adminhtml')->__('ID'),
            'width'     => 5,
            'align'     => 'right',
            'sortable'  => true,
            'index'     => 'user_id'
        ));

        $this->addColumn('username', array(
            'header'    => Mage::helper('adminhtml')->__('User Name'),
            'index'     => 'username'
        ));

        $this->addColumn('firstname', array(
            'header'    => Mage::helper('adminhtml')->__('First Name'),
            'index'     => 'firstname'
        ));

        $this->addColumn('lastname', array(
            'header'    => Mage::helper('adminhtml')->__('Last Name'),
            'index'     => 'lastname'
        ));

        $this->addColumn('email', array(
            'header'    => Mage::helper('adminhtml')->__('Email'),
            'width'     => 40,
            'align'     => 'left',
            'index'     => 'email'
        ));

        $this->addColumn('mobile', array(
            'header'    => Mage::helper('adminhtml')->__('Mobile'),
            'width'     => 40,
            'align'     => 'left',
            'index'     => 'mobile'
        ));

        $this->addColumn('is_active', array(
            'header'    => Mage::helper('adminhtml')->__('Status'),
            'index'     => 'is_active',
            'type'      => 'options',
            'options'   => array('1' => Mage::helper('adminhtml')->__('Active'), '0' => Mage::helper('adminhtml')->__('Inactive')),
        ));

        return parent::_prepareColumns();
    }

    public function getRowUrl($row)
    {
        return $this->getUrl('*/*/edit', array('user_id' => $row->getId()));
    }

    public function getGridUrl()
    {
        //$uid = $this->getRequest()->getParam('user_id');
        return $this->getUrl('*/*/roleGrid', array());
    }

}

But it is not working.