This could just be me, because it's past midnight and I might not be thinking completely clear here. But, the URL to this "latest news" page is showing as:
Nevertheless, 'about-us' is a page and not a category or post, right? So how are you associating a blog category as a child of a page then trying to get a feed off of it?
Go to your "post" menu, then "categories" option. Find the category you are using for your blogs, put your mouse of the "view" link found below it. In status bar, use that address plus /feed at the end of it to get proper RSS Feed link. Any sub-categories will fall into that feed as well. (Note: You can right click the "view" link and select copy link location, and then paste that into feedburner, along with feed at the end.)
For the navigation menu "latest-news". Within your wp menus editor, change that latest news menu option to the category your using for latest news within the menu area of the dashboard. Then, it should properly show the blog listings.
Hope this helps.