Hello, @Saira,
Actually, the images are not stretched because of my code check here I remove the code, and then the image started appearing 1 in a row https://postimg.cc/NKYZPGhd see the image already appears like this. By setting two columns with the given code mine the image results much better than it appears in 1 column in 1 row. Please check this image: https://postimg.cc/XrJkvt9V
Secondly, I have found a CSS code on your site that is set for the width and height of the images check here: https://postimg.cc/yDkpGDQX by default WooCommerce handles the product/category images and WooCommerce has an option to set the product images size. You can find it in the Theme Options >> WooCommerce >> Product Images: https://postimg.cc/2qH6SXFf using a CSS code to set the product/category images size is not a good way when the plugin provides an option. Please try to remove that CSS code that was added to set the width and height of the product images and then try to set the size using the options the plugin provides. The CSS code I share with you to show the 2 columns on mobile is not responsible for the images stretched.
Regards 8Themes Team.