COCKTAIL SAUSAGE IN BAR-B-QUE SAUCE
This is fast and usually liked by most people. The sausage can be put in a crockpot with your favorite bottled sauce, simmer, place on a tray or in a heated container and serve. (A senior moment, I can't think of the name of the containers that use the canned heat)
Chicken salad sandwiches. The bread can be trimmed in advance and frozen, on the day of, thaw, spread on the filling, cut in quarters or fancy shapes and serve.

CHICKEN SALAD
My niece's recipe is 1 boiled chicken breast processed in the food processor until it looks like sawdust, add 1 boiled egg, process, add sweet pickle relish to taste, about 1/2 small jar, mustard and salt to taste, lots of black pepper, and enough mayo to make spreadable mixture. This makes 4 or 5 sandwiches with plenty filling. The same can be done with ham.

HEAT AND SERVE FOODS
If you have a Sam's club or something similar in your area, check them out for frozen meatballs, hot wings, chicken in different flavors, quiche, and several differen desserts. They are good, and all that is necessary is to heat them and serve. The flavored chicken breast, I cut into bite size pieces and serve with different sauces, teriyaki, honey mustard, bar-b-que, ranch, etc.
They also have large bricks of cheese that you can cube yourself, or buy it already cubed.

Check this site for the sauces, they have some very good recipes.
If you are doing the food for that number of people, make it easy on you, because it can be very stressful the day of getting it together.