Holy Cow, I'm all for reasonable dress codes to keep kids from showing up in jeans and t-shirts, or dressed like hookers, but a 'contract' limiting or controlling every aspect of an off campus 'social' event just seems a little over the top to me!
I guess I'm glad to be old, I sure didn't have to sign off on anything to attend my high school prom or ROTC Ball back in 1982. Just looking at that contract, at my prom we broke just about every rule on there! I had a room at the hotel, we came and went from the dance to the room, or to drink in the hotel bar (legal age was 18 at the time) and my date's dress had a "plunging neckline"!

Senior prom is an important part of finishing out one's high school time, but it should be a fun party, not a lock-in with suspension of a few constitutional rights! Honestly, if I'd been presented with that paperwork, even back in the 80's, I'd likely just pass on the whole deal.