Help vs aoe teamcomp

So I just went up against a team comp that consistited of Top- malph, mid -ammumu, jungle hec, bot- sona twitch. Earlier in bans I banned Zyra, MF, and Rumble. They would have put zyra mid , mf bot, and rumble top if they were not banned. We won early game hard but got crushed late game because their team fight was just to good. Any suggestions to beat them in the future?