There is no reason for your mother to wait or to continue paying a lawyer who is not acting in her best interest. Your mother can do a do-it-yourself divorce. That's what I did when I divorced my husband many years ago. I completed and filed the papers with the court, served the papers on my husband, waited the appropriate amount of time, made an appearance in court and we were divorced about a year later.
The difference is that we had no children or assets to fight over who gets what. Your mother's divorce could be more complicated and she'll have to be very careful to make sure her rights and interests are protected.
Do a google search on "do it yourself divorce" and you'll find several sites that offer the forms for every state in the US.
Nolo Press used to have some good booklets that were helpful in self representation in a divorce. Take a look online and check them out at the library if you can't afford to buy them.