Hello BP

I'm still fairly new to the game and need to help a friend out with Real Estate information. Here are some background information to help with his questions. He had a member of their family recently pass away leaving their spouse with dementia behind. They are getting to the point where they need around the clock care and need to sell their house  where they lived to help pay for the health care and living expenses .  The house is located in AZ and the spouse will be moving to WA.  So his question is  what is the best way to go about selling the house and avoid the capital gains tax? They want to keep as much money to pay for the care. Also the house is in the spouses name with dementia, is that going to pose a problem legally when selling the home? Any help will be greatly appreciated! 

Thank you BP members!