B2 to F1

[roy@edmonton]

I am posting it on behalf of my friend. My friend was in US on H4 during 2005-2009 when they applied for GC. Because of some unfortunate event she had to leave in a huff and her I-485 adjustment of status got denied as USCIS couldn't reach her.

She came back on Visitor's visa last year June 2016.. went back to India for 10-15 days and back on Visitor's visa on 10th December 2016. Now she has applied for F1 Visa following all Sevis regulations. USCIS got her application on 04/25 and she is trying to enroll for the summer classes in the University that processed her I-20. Her Visitor's Visa expires on 06/08. What are the chances that the F1 will be approved. The International admission department scared her a bit saying since she has a history that she tried to immigrate it will be difficult to get the F1. 

Some more additional Info:

Her school gave a tentative start date of 2nd June 2017. Remember her B2 Visa expires on June 8th. And the USCIS receipt date is April 25th. One other factor that I think might affect is that she has a 14 year old son who is applying for F2 VISA along with her. She is already in this country back to back on B2 with a 10-15 day gap in between - so for sure her application for B2 extension might have been denied. How long does it take for USCIS to decide if they want to deny the application?

Any help is much appreciated