I find some questions are easier than others to reply to, my mums questions about where my brother is, floor me, I am still emotional about his death so they catch me off guard, I found it incredibly difficult to start with but now mum is at the stage where she now doesnt ask, despite lots of photographs around, or I am able to deflect the question very easily.
To the question about going home ( mum moved in with me recently and the better she gets because of brilliant carers and routine, the more she asks this) I now reply that the doctor said she could either stay in hospital ( following a fall) or come to me to get better and as soon as he says it is ok, she can move home ( that isnt going to happen) and she seems happy with that.
You dont say where he lives, alone, care home etc, but maybe for now you could play along, even say you will get some holiday brochures next time you are passing a travel agent, and ask where he would like to go, similar for 'home' find a reason not to do it now.
The best advice I read here is never say no, that just puts a barrier up