My husband and I went through this when we bought our house... a good non-butyl degreaser cleaner that can be purchased at a commercial cleaning supply store does wonders on the walls. We then painted all walls and kitchen cabinets with KILLS primer available where paint is sold. We used Murphy's Oil Soap two or three times on all the woodwork and we also deep cleaned our carpets three times over two months... and we purchased an air purifier. It takes a lot of work but within three months there was not a hint of smoke smell in the house! Best of luck to your friend... I hope this is informative.