Relatives are like fish, after 3 days they really start to stink!
In yoga we are taught to block out all surrounding sounds and just listen to our breathing. I would start now! Start practicing like making a list of things in your head while they are doing the screaming over each other thing.
Think something like colors and try and see them. Red, purple, blue, orange, etc.... and see if that helps. A whole month? Why a whole month? and where are they staying? Can you make lot's of appointments during the visit so you can escape.