Maybe you should just save your money for a down payment on a house
Thats' easier said than done in some states where property value is insane.
In NJ, if you aren't married it's very tough to get a house.
Literally nothing is less than $250,000, and that gets you a craphole.
So you must be a 2 income family.
So if he lived here, the few grand he spends doing that basement will be chicken feed towards a down payment.
I'm assuming there is no permits being taken out, if that were NJ, that would be a big mistake. As long as you pass it off as an office or TV room (basically anything but a bedroom) the codes aren't that hard to abide by in a basement.
This way if your mom sells the house one day, they don't come down on her very hard.

