I think OP meant to say that he is currently in the US on VWP, and is getting married to his USC partner (who is co-sponsoring with his mother).
Hopefully other people can chime in with specifics as I don't know much about co-sponsoring.
* OP if you're not in the US currently, you should cancel your plans to enter by VWP and file a K1 visa instead.
** if OP is already here on VWP, he can marry and adjust as nobody stopped him at the border. OP, just be prepared for more scrutiny of your relationship.
