Most anything that can be eaten with the hands is acceptable. A fruit tray would be nice, finger sandwiches, pizza, hot dogs, hamburgers, pickles/olives/ celery/carrot sticks, chips/dips, cup cakes, brownies, etc., all would be acceptable. Keep it simple and make it easy to eat and easy to clean up. It does not have to be elaborate to be nice. BTW, Happy Birthday....to someone.
Any foods will do as long it can be eaten. You could hire a catering services for that important event or try these easy birthday party food . Hope it helps.