Very tough rode ahead for you if hubby is truely a mama's boy. Better to set the boundaries now, will be easier in the long run.
If he can't call her and explain that it is not a family vacation and no parents are invited then your only other choice is to do it yourself. Understand this will mean a battle of control between you and her. Your husband will not be very supportive in this battle, but will be yanked back and forth between the both of you. To bad he can't handle this situation. That would help alleviate the blame being put solely on your shoulders.
Just remember if she had enough brass to invite herself, meet that same brass with a good dose of yours. People can only take advantage of you if you allow them to. Easy, no, but after the first few times, it does get easier. Be kind but be firm.
I like the saying that a daughter is a daughter all of her life, a son is a son until he takes a wife. Perhaps hubby needs to know that.