Many adults undergo surgery to correct spinal deformities like your mothers. The surgeries are called osteotomies and involve removing bone from the spine and, if needed, lengthening it in some areas.
When a surgeon evaluates the type of surgery that may be needed, he or she does take into account the patient’s horizontal gaze, which is how the person is able to look straight ahead, with the gaze parallel to the floor.
It would likely be a good idea for your mother to visit an orthopedic surgeon to see what options she has to make corrections to her back.