Stroke victims wife needs to sell home ... rights ?

hi my grandad had a severe stroke last year, we are trying to get him home as this is his wish and care for him. they both brought a house a few years ago. both names are on the documents and my nan is my grandads obvious next of kin. my grandad since the stroke has been labelled as mental unfit to make serious descions such as controlling his money, property etc. in order to get him home, my nan needs to sell there 3 bedroom house as it is unsuitable and get a 2 bedroom bungalow as it is much more easier as he cannot walk etc. would my nan be able to sell the home even tho my grandad cannot say for himself since they both co own the property or do both people have to be in fit mental state etc. i am waiting to talk to citizens advice shortly , but would like to hear peoples input kind regards