If there is nothing physically wrong with him, then she could to try some major cleaning in the new home. If the previous owners had pets, he could be smelling them, even if their odor is undetectable to human noses.
I would definitely keep him confined to one room to begin with, but she might be well advised to clean the room thoroughly before forcing him to stay in there. A lot of people use the laundry room as their pet's room so there could be a lot of pheromones left behind. She should use a dilute bleach solution to clean the floor of the laundry room and wash the walls if possible. Make certain that his litter, food, and bedding is the same as it has always been and suggest she continue to use the pheromone plug-in or spray. If it can be avoided, do not wash his bedding-- it has his own pheromones on it which will comfort him.
Whoever usually is the one to pay attention to the cat should continue to do so regularly so he isn't "banished" from the family. If he's used to being part of daily family life, he'll be further upset by being ignored. She could also contact Dr. Kelly Moffat, a veterinary behavioral specialist. It will be somewhat costly but it may help. http://www.drmoffat.com/
This is no doubt a tough situation and I have been in a similar one. I'm a veterinary technician and I even had the vet at my disposal for daily visits and referrals! I ended up having to euthanize my beloved kitty because nothing I did stopped him from urinating all over my house after my first child was born. He simply wasn't able to adjust and I dealt with the urine for 10 long months before I had to make that awful choice. It was one of the hardest decisions I've ever had to make. I hope that your friend's kitty isn't as stubborn as mine.
Also, if it comes down to the fact that his behavior is not changeable, PLEASE do not suggest that your friend take him to the pound. That is not a solution. He will just become someone else's problem when they unwittingly adopt him and the cat will only suffer more stress from being passed around. If she is able to find a home for him privately with the new owner being fully aware of the situation and willing to work with it, awesome, but it's unlikely someone else would put up with that behavior. I hope this helps even if it may not be the response you were expecting. Best wishes to your friend.