MrXHellboy

This plugin will provide you a new widget, showing the last modified items. 
You can customize the widget with 5 settings: 
– Title 
– Amount 
– Text between title and date of modification 
– Show the date 
– Post type.
<h3>Development Blog</h3>
<a href="http://online-source.net/category/open-source/scripts-wordpress-plugins/" title="Online-Source WordPress plugins" rel="nofollow ugc">Online-Source WordPress plugins</a>

Last modified items Widget

List your last modified items through a widget. Quick and easy.

linknacional

The <a href="https://www.linknacional.com/wordpress/plugins/" rel="nofollow ugc">Post Updated Date for Divi</a> is a simple plugin, that displays the date of the latest post update or modification, instead of the publication date.
Dependencies
No dependencies.
User instructions
<ol>
<li>
Search the WordPress sidebar for ‘Posts’;
</li>
<li>
In the post page, look for the date column;
</li>
<li>
The displayed date, should be the date of the last update to the post, instead publication date.
</li>
</ol>

Post Updated Date for Divi

Shows the post updated or modified date for divi blog posts. Will show only those posts are modified or updated.

Last modified items Widget vs Post Updated Date for Divi