Keep it simple!
Bubba burgers are great and easy to cook.
Baked beans usually go over well with everyone.
Chicken breast (boneless) can be had cheap at Sams or Walmart and also easy to cook.
BBQ can get pricey but again, simple and most like it.
Chips are easy, Doritos, Sour Cream/Onion, BBQ, Fritos, Salt and Vinegar ...etc.
I'm personally not drinking (I doubt it anyways) but having a little bit available would suffice.
Water and Soda by the masses would be good as well.
Paper plates, Plastic utencils, napkins