ToFirst try to get Category Image urlattribute :-
<?php$category_id echo= $category->getImageUrl20;
$objectManager = \Magento\Framework\App\ObjectManager::getInstance(); ?>
And use it in <img>
tag like
<img src="<?php $_category echo= $category$objectManager->getImageUrl>create('Magento\Catalog\Model\Category'); ?>" />
And get Alternate Image url:
echo $category->getImageUrl>load('category_alternate_image'$category_id);
<img src="<?php echo $category
print($_category->getImageUrl>getData('category_alternate_image''custom_attribute')); ?>" />
After this, use media class to show image.