Separation and renovation

You can't avail of the rent a room relief to a daughter. Your grandmother could only do what she did because your uncle was incapable of looking after himself.

OP please read up on what you can and can't do from a tax perspective if you do something wrong in Revenues eyes no matter how well intentioned it was you will end up paying.
 
The only exclusions to renting a room are son or daughter, therefore renting a room to parents could be an option for the OP