How Do I Keep From Gaining Weight At Grandmas House?!?!?!?!?

Ok On July 1st im going to my grandma's house for a week and it her birthdays too. im trying to diet because i have a six pack challenge going on with my friend and im not fat but i have a little lower belly fat that i am trying to get rid of for my abs. so my grandma called and shes like " i baked 7 pies today!" and im like yay grandma thank you :/ but in a happy voice even though i wasnt pleased! anyway we are also making a birthday cake (its a carrot cake with cream cheese icing) so i will have to eat that on top of pies and ice cream and she just keep shoving in the junk! if i dont take it she will get really sad and i hate to disssapoit my old granny! do i just take smaller portions or what? and to top it off i dont have any way to exercise at her house because i dont have a gym membership there and she has no equiptment. she does have a pool though and a trampoline