Hi!
I'm allergic to dairy and I went to MNNSHP last year! I didn't think I'd get to eat much but I was pleasantly surprised! We got the usual chocolate candy - Snickers, 3 Musketeers, etc but also Starburst, Skittles, Smarties and the like.
I believe you can go to Guest Relations before the party to tell them about the allergy and they will give you a special bag with safe treats and maybe a pencil or coloring book or something. (I don't remember off the top of my head but I remember it was something non-food) I don't have a cross-contaimination risk so I didn't do this. I just got what everyone else got and split it all with my DF and parents.
DF was especially impressed because he thought all he'd get was "cheap candy" like Tootsie Rolls!
Have fun!!