S.L.
A.,
If your mom is offering to take your little guy... then let him go! It will be sooo less stressful for everyone. He will just be @ grandma's playing & you will be able to get things done a lot quicker & more efficiently if you don't have to chase him around all weekend.
As far as him coming "home" to a new/unfamiliar place... just make sure that when you bring him home you are very cheery & full of smiles. Say "look baby (whatever your pet name is for him) -- look at our new house... this is gonna be fun!" Let him unpack a little with you... maybe some of his clothes & the toys that you do have for him...
Just because it is temporary doesn't mean that it has to be unfamiliar & scary... Think of it like a vacation or camping or something. It may be all new, but it's something waiting to be explored. Keep him occupied & make sure that he has a few comfort things that he can relate to & know that everything is ok & he is still going about life w/mommy & daddy by his side.