The torn disc may end up having to be surgically repaired but whatever she does, make sure she gets at least THREE consults with different NEUROSURGEONS. DO NOT, I repeat DO NOT let her (or anyone, for that matter) have spinal surgery by orthopedic surgeons, no matter how well they come recommended. Neurosurgeons will not touch someone that an orthopedic surgeon has worked on and if you suffer from neurologic problems as a result of surgery at the hand of an ortho, you're screwed.
As for the degenerative disc disease, an honest surgeon will not operate on anyone for that, it does not have a good long term result. Tell sis to find a good chiropractor, avoid impactful and/or twisting/turning activities (things like carnival rides, jogging, bungee jumping) start taking glucosamine/chondroitin (if she can take it) stay as far away from refined sugars and flours as possible, and weight train, properly, seriously. The only thing you can really do with DJD is remain strong and active and flexible as possible, strong muscles can support the understructure to a degree. Yoga can help, but you need to start early and it needs to become a regular, daily practice because flexibility vanishes remarkably fast when you stop moving.
Oh, and tell her to invest in a good bed, like a sleep number or (my personal favorite) Tempurpedic.