I was four, my brother was 8 when my father died. My mom had to keep working, so we got passed around to family members alot in the evenings, and they all thought it was great to take us to McDonalds, Burger King, etc... when all we really wanted was to sit at a table and eat a home cooked meal.
Although you don't know the family that well... you know kids, and what they like to eat. Maybe you and some of the other parents can put together some freezer friendly foods for the family that they can take out of the fridge and heat up for dinners when they don't feel like cooking. Maybe get a couple of the mom's together and offer to donate some time for cleaning at her house, as she will undoubtedly have lots of company in the upcoming weeks, and no energy or will to clean. Even offering to do some grocery shopping for them would help, ask her for a list of what the kids eat and anything else they might need right now, or just get her some of the basics like toiet paper, paper towels, hand soap, etc.
Maybe have a class meeting with the other kids while he is still out for the funeral, and make it a point to tell them that even though this boy had been a bully in the past, that his father died and he would really need friends right now, and to try to be extra nice to him for a while.
I know from experience that all I really wanted was to have my Daddy back, but all the people being around and helping my mother really helped her to be able to concentrate on helping us cope and less on what the house looked like or what to cook.
I wish you well in finding some way to help the family!