How can I clean an old wooden house to get rid of odors?

You need to find the source of the smell. Is it mold?

Dampness?

I live in a really old house as does my neighbor. It could be a pipe leaking or roof leak that is causing a mold problem, I would start by checking under all the sinks to see if the cabinet bottom is molded and rotting. Then check up in the attic, basement for signs of a leak. Could it be coming from your basement, if you have a musty or damp basement - try putting a fan to exhaust out of the basement window or vent,

My neighbor had the plumber throw a whole pack of rat poison under the house after rats chewed her bathroom pipe...... well she must have killed a bunch of rats plus the possum living under her house..... boy did that reek and then the flies afterwards were a nightmare too. So someone might want to check for dead critters.

To get rid of the odor, I recommend you get Room Shocker which is a professional deodorizer.... https://www.amazon.com/Biocide-Systems-3220-Shocker-Eliminator/dp/B00B3XUBES/ref=sr_1_4?crid=2R3IJK2CCILY3&keywords=room+shocker+odor+eliminator&qid=1568431544&sprefix=Room+shocker%2Caps%2C266&sr=8-4 if this is more than 1 room, it comes in 2 packs and 4 packs to do a whole house. Its also carried at home stores because its what contractors use.

Try washing down walls and sealing the wood walls. Clean all fabric items. Can be out rugs etc.

We own an old house, and a dehumidifier and improved air circulation in the basement cleared most of our problems. We also improved where the gutters drained and that helped, too. Air quality is important, so consider an air purifier for living areas when you can't leave windows open or if you have allergies.