I'm sorry to hear about your loss.
I think you have some great ideas!
Have you checked out the fat free vegan site? She has some yummy looking appetizers. http://blog.fatfreevegan.com/category/a ... s-and-dips
She has mushrooms stuffed with pesto mashed potatoes, maybe that stuffing would be nice in the cherry tomatoes.
What about simple cucumber sandwiches, bread/hummus/cucumbers?
You could do tortillas with salsa, maybe guacamole and a bean dip too.
Does it have to be finger foods? Otherwise you could make a couple of salads, maybe potato and pasta.
Veggies & dip is easy.
Is sushi too weird for them? If not, to save time, you could order some from a restaurant.