Yah.. I ma in F-1 and stilll on the way to graduate.. meaning that not graduate and I have the answer for you as I have invited my mum to visit me here and she is with me.

The Doc that I had send for my mum .. ..   A summary of University fee for 4 quarter of the year 2008, means that i had taken summmer classs too. . ,  An invitation letter written by International Student Officer, The class schedule of the last quarter  and I had one letter written by a Doctor just making strong chances to get visa as I am worried a little bit and want to see my mum. . . and  from my mum part she just showed the bank balance of 10 lakh .. . ..  hope this will help you a lot if you want them to be in states.