RESPONCE CARDS

Well, i asked people to respond back on my R.S.V.P by march 26th. I had gave everyone about 3 weeks notice.
Only 4 people have responded and i already new they where coming in the first place.
Well, my problem is its time to order the cake and food and we invited about 100 guest, What should we do?? should we count all are guest and if so we will have TONS of cake & food left. Or just count on who has R.S.V.P??
I dont want to my more then i have too, it will be a waste.
Any advise...