My gradmother saw all sorts of people. One time she told me that several woman came into her room and left their babies with her to watch
even though she told them she was too old to babysit! I told her I would talk to the nurse on duty and make sure that didn't happen again.
There was also a little girl who used to run in her room and hide. I would look for the little girl and assure my gran she was gone.
It is best to figure out how to play along and alleviate his anxiety than to try to reason with him, although perhaps now he can still understand that he has hallucinations, eventually he won't.