Yes, her dad co-signed the loan, without her dad taking on reliability, there is no way in hell she wouldve ever gotten that loan. And considering that he had to do the same for Derek, that's a serious amount of dough, so yeah I too believe he had to put some serious colleteral up for it.
And I very much agree, that it was incredibly naive from Maya to not go the normal student loan route, I guess she thought with Derek getting the same treatment, that thats how its supposed to work. But maybe both of them underestimated just how much of an control freak their dad is, and now she has to pay the price. If nothing else, it should be a 1st class life lesson tho, never trust anyone when money is involved and always do your own research.