I don't see any reason to mention her Mom unless your daughter mentions it.
Just have the talk and see what happens she may want to stay with you and she may not and have somewhere else already set up.
Your daughter being in her mid 30's is too old to be moving back in with you if you want my honest opinion.
I doubt if either of my 2 daughters in their 30's would even ask me to move back in they are far to independent.
