Hello. Welcome to Just Answer.
There are a few easy steps you can take, which should help tremendously in getting rid of the odor:
The most important step is probably placing a dehumidifier in the affected area. That will help with any residual moisture that may be hanging around.
Some people have reported success with using vinegar to eradicate the unpleasant odor.
I don't know if your walls are made of a material that you wouldn't want to spray vinegar on, but I have seen that suggested. Others have set out pans of vinegar.
Lastly, if you can get air circulating in that area, this too will greatly aid in eradicating the smell.
We still smell the must old house smell in the basement.
Our basement walls are made up of concrete blocks. There is a old well water tank and a little bit of old insulation. Do you think any of this is also holding the smell? What about the rafters? They probably are also holding the smell. Can were spray these wood beams with vinegar too? Do we just use a spray bottle? Or is there a comercial item we can use to cover large spaces? How much vinegar do we use? There is no water in the basement now, but the smell is still there.
Yes please help me afterwards. I wouldn't want you getting late for church. Do you live in the East Coast?