Dairy free egg free...what the heck nut free bday desert options for 4 yr olds?

My Daughter's bday is coming up. A small gorup of 4 yr old will be in attendance. I know at least one boy is allergic to milk and eggs. I really do not want to bake a dairy free cake myself. It will be a hot Sat early 10-12. I think i may be o.k not doing cake. What can I do that the kids will be just as excited for? Sorbet..Jello with gummy fish? ( under the sea / mermaid theme fyi)Novelty popscicles. But what else? Something else? I've seem a recipe for a watermelon cake usuing real watermelon and cool whip. Is cool whip dairy/egg free? I know I can just do a reg . cake. Most Moms with kids with allergies bring their own treat. Since it will be only about 6 I'd prefer for everyone to be included. Someone will have a great idea I can feel it!!!