1916 bungalow - Removing cigarette and animal odors
Replacing dry wall will help, remove all carpets and padding , painting your walls and refinishing the floor will help.

When you pull the old dry wall and sand the floor - a stripped house..

Then rent the OZONE Generator - seal off the house, stay OUT of the house for several days. The Ozone can kill you.

Have a method to turn off the generator with out going inside. 

After you have done this open windows and doors for several days at a time, do not go back into the house for long periods while you open windows and doors - let it 'air out'. After 3 days you should be able to enter wiht out issue. 

Install your dry wall, paint them and refinish your floors.