My sympathies to your mother. If she hasn't already, contact TNA - trigeminal neuralgia association. Its not geniculate specific, but its the best assoc. i have found for cranial pain. The members have local area support groups that accept cranial neuralgias for what they are and need not be TN specifically. I now have friends who had the same fate as your mother - not responsive to surgery. Some 100% failure after multiple attempts, others had success after 3 or 4 tries. Most do find success after 1 surgical intervention. (those that have to resort to surgery, of course)
As a sufferer of Geniculate with a daughter, I have to tell you that you may feel worse than your mother does. GN sufferers will try about anything and accept any trade off to be rid of it. Its when all options fail that it is a real tragedy, like your mom. She's lucky to have a caring daughter as yourself. Rotten results isn't what anyone aims for, but surgery can and does offer people their lives back. My own daughter has fears of what I"ll be after my surgery (pending). Again, my sympathies to both of you, but please do not disparage what is can be successful. I do advise that surgery be only for those with maximum out of control GN.