Can I move my 9 year old cat?

Can you move a 9 year old cat and separate it from another cat? I live an 1 1/2 hr away from my cat, and him and my mom’s cat are best friends. He has been hiding up in her bathroom closet for the last few days (I think because they have been renovating), and is still eating, grooming himself, etc., but he will not come down from the closet. When I visited today he did not appear sick, just scared maybe? He has lived in her house all of his life, but I have moved in/out for college throughout the years and moved out permanently 6 months ago. My siblings have also recently moved out, and my mom goes back and forth from her boyfriend’s house. Her boyfriend’s daughter and friend moved in full time to help renovate, and they take care of the cats when my mom is gone. My family doesn’t think I should separate the two cats, but I really miss my kitty and he doesn’t seem to be adjusting well to all of the changes. Would it be more stressful to move him here, separate him and my mom’s cat, and introduce him to a new cat (my boyfriend’s)?