I just did some research on this, and according to the Mayo Clinic, there are different causes:
"Trigeminal neuralgia can occur as a result of aging, or it can be related to multiple sclerosis or a similar disorder that damages the myelin sheath protecting certain nerves. Less commonly, trigeminal neuralgia can be caused by a tumor compressing the trigeminal nerve. In other cases, a cause cannot be found."
Does your mom know the cause? There are different treatment options, depending on the cause (if known), including medication, injections, surgery, acupuncture, biofeedback, electrical stimulation of nerves and different therapies involving vitamins or other nutrition.
You can read about treatment options I mentioned here.
Has your mom tried any of the other options, and is she wanting an alternative medicine treatment (like acupuncture or biofeedback), or is she open to other types of medication or surgery?