She needs to consult with an attorney in her area who handles DUI cases. It sounds like she was probably stopped for a lane violation and then arrested for the DUI along with the lane violation. If you truly want your mother to be prepared, then she should consult with 2 or 3 attorneys and choose the one she feels she can trust the most. Also, it is not a bad idea to ask her more discrete friends for a referral. It is very important for her to know that she may face an administrative suspension of her license if she fails to demand a hearing within 10 business days. The Georgia Department of Driver Services now charges $150 for these hearing requests. If an attorney she meets with does not know about that policy, move on to the next one.
Robert's answer is absolutely dead on. Most DUI defense attorneys offer a free initial consultation and will help her with the request for an ALS hearing without charge. She should interview a couple of attorneys to get a feel for expertise, experience and strategy. A referral from someone who has used the attorney's services and had a good outcome is the best way to find an attorney who will do a good job for your mother. I wish her the best in what is a trying and stressful situation.