Stephany,
I am sorry to hear the news about your mother. I know this past year has been so intense for you and your family. As suggested, I would scurry to a major comprehensive cancer center and get another opinion. Keep in mind, though, that with the radiatin your mother has already received, she may not have any options other than surgery and if the cancer is spreading, that surgery can keep getting more and more invasive.
With the outcome your mother's medical team has determined, it might be better at this point to get your mother into hospice care. They team that attends to her needs will be better equipped to keep her as comfortable as possible as well as help deal with some of the issues around this intense of a disease and diagnosis.
She may have to tell them she is not seeking further treatment while you get that part of her lfe managed. If treatment options arise in your second (or third) opinions, you can always change the course plus many doctors will work with you and tell hospice the treatment is intended to minimize pain and discomfort versus cure the patient. This type of palliative treatment is even allowed in hospice.
My last words are NEVER GIVE UP! As long as your mother is alive and wants to fight this horrible disease, be her advocate. Find what options are out there and push the medical folks towards that goal.
Again, I am sorry you are having to endure such an intense part of life.
Ed