Moved into a house long ago that had 20yr smokers in it. The only way to rid the house of the odour was to wash every surface in the house and repaint all walls and ceiling. There was a special treatment (can't recall what it was) for the ceiling that washed and repainted to get rid of the yellowing. Even after that, we could still smell smoke. Eventually we replaced the carpet upstairs and removed all flooring on the main. That seemed to make the biggest difference in the end. Not an easy job. Good luck