One thing that travels well as long as you have a cooler is a chocolate truffle that you can put together when you get there.
Just make a 2 layer chocolate cake, you can leave them in the pans if you want.
Next, make 2 packages of chocolate pudding & keep them cold.
Also purchase quart size container of heavy cream and either bring sugar with you or make sure they have some at their house where you are going.
When you start preparing you need a triffle bowl or something very deep. Cut one of the chocolate cakes in half and lay it on the bottom, put chocolate pudding in the center and bring it out near the edges of the cake then do the same with the heavy cream you have whipped.
Continue with the cake, pudding, cream mixture for another 3 layers and top with whipped cream and some shaved chocolate sprinkled on the top or just chocolate jimmies, whatever you prefer. People will think you are clever but it is easy as can be. I have also added things like cherry pie filling on top of the pudding just in the center, people do not know it is there until they taste it. I can almost guarantee there will be little left over, people just love it and it is easy.
Have fun & enjoy.
Carolyn