Cakes will be frosted in buttercream, but will have a few rolled fondant decorations. I am leaving on vacation on wednesday and the client will be picking up the cakes at my house on friday. Can I complete the cakes and then cover and refridgerate with the fondant on them? thanks in advance!

Yes, put your cake in a box and wrap the box with Saran Wrap or even a garbage bag to help keep out moisture. When they come to get the cakes, tell them to leave them in the wrapped covered box til it comes to room temp before taking the cake out. Even if there is some condensation after all that, the fondant will eventually dry out.