Fondue! You could do chocolate with fruit. Cheese with veggies. Beans and cheese with Fritos and crackers.

That is a lot of people to have in one house. Is there somewhere else you could move it to? My sister-in-law had her baby shower at church. There was plenty of room for a lot of people and there are tables and chairs already there so they didn't have to rent any. If you could move the shower somewhere else you could also have some messier foods. Even if you have to rent a room somewhere it may be worth it.