The only thing that really helped me with migraine is practicing Yoga on a regular bases, I don't know if it was the fact that my neck didn't have so much tension in it anymore or that I learned to breath differently, but after about 6 months of yoga, my migraines just stopped.
There are a lot of different reason for migraines, there might be some dietary changes that might help. However, for a lot of people with chronic migraines the only and best medicine are not alternative, but blood pressure related pills that they need to take everyday. Your mom should not neglect this, and there is no reason for her to suffer so much. There are a lot of progress in migraine research and treatments and here are cures that work.
Also, and I don't want to worry you, it might be symptoms to other illnesses, she should definitely see a neurologist for start, and then probably a blood specialist and a nutritionist and check that there's nothing more serious then migraines.