C.J.
I don't know if you want something packaged because it's so close to the party, but if you have a little time to spear you could make some weight watchers cupcakes.
All you need is 1 box cake mix - any flavor, and 1 can soda - any flavor. I have done white cake mix with sprite. You just add about 10 ounces of the soda to the cake mix and fold it in. Then bake as directed on the box. Then frost them after they have cooled. Really the cake is sweet with out the frosting, but these are kids we are talking about.
This way the kids with the allergies can have cupcakes just like the other kids. It doesn't take too much time to make these, but if you don't have the time I like Sherry's idea of rice krispie treats. It's great to see other parents aware of other kids allergies. Good Luck.