I have the opportunity to purchase my Mother's house. It is an old house with need for LOTS and LOTS of repairs, renovations. I was thinking, if possible I could turn the dirt basement into either another bedroom with bath. Is this going to be expensive and what would have to be done besides concreting the space?
Without seeing your basement, it's hard to comment on what you will need to convert your basement.
The concrete alone will be expensive. Also, unless you want to consider digging out some of your basment so you can retain ceiling height in the basement. Although you may not be able to due to your existing foundation.
Also, when cememnt cures, it will release a tremendous amount of moisture into the air which will bring your humidity levels to dangerous levels. Unless properly ventilated, you will risk mold growth.
There are so many considerations with a project like this, it may be cheaper to put an addition onto the house.
Most importantly, you must make sure if you turn your basement into a living area that you have proper air exchange. Your basement must be healthy, free of mold and pathogens.