How Old Is Too Old To Change A Name?

Ok Mimi, ya did it to us again....Tissue please...
Moms cat Rachel spent alot of time with my grandpa while he lived with mom, she was the one who came to get mom when he passed in his sleep. Mom has since turned his room in to a play room for the kids, Rachel has not been in the room since the day he passed, she just sits in the doorway & stares