right sidebar will not post articles after upgrading

I just upgraded my sister-in law’s blog. I get the error code:

Call to undefined function: c2c_get_recent_posts() in /homepages/15/d218557347/htdocs/wp-content/themes/digg-3-col/sidebar.php on line 12

on her right side bar. The recent articles will not post. Does anyone know how to fix this. I would be deeply grateful. thank you.

bill