What can I make for my vegetarian nieces this Christmas.

I always try to make a special dish for my two nieces that don’t eat meat, plus something light for the family members that probably shouldn’t eat meat. Let’s just say I have some plus sized family members. Dinner is at my Mom’s and she’s a good traditional cook, but anything new or wild throws her and it doesn’t come out well. I like to try new things and they really appreciate the efort. Any ideas?