Welcome to the forum. As you know, we are not doctors so we can not prescribe medical advice for students, especially remotely, but I do have a couple of thoughts for your student.
Yes, yoga can help, possibly, maybe. It all depends. There is always a trade-off to be made in rehabbing from any injury. No movement at all creates lots of problems in the body. Too much movement re-damages the area we want to heal. The trick is to find the optimal amount of mobilization: the Goldilocks' position, if you will. Where this is varies dramatically from person to person depending upon the location and level of the injury and the student's normal ranges of motion. For this reason, the best way to approach yoga as therapy is for the student, her yoga teacher and her physio or health care provider to work together as a team to find a way forward. Sometimes this will require much trial and error.
I would suspect the first thing to do is to deal with the inflammation. I would invite you and your friend to read an article that I posted in a Newsletter a while ago about Earth Chi
because it deals directly with the causes of inflammation, its consequences and ways to help reduce it. 20 to 30 minutes a day of "earthing" (which as you will read in the article is simply getting connected to the earth) may reduce the inflammation enough that yoga can be effective.
Once there is no pain, then have your student begin with some very simple Yin Yoga work: maybe just an easy Sphinx pose, followed by Butterfly. These can be followed by some easy Cat Breath: just undulating the spine and down synchronized with the breath. She may benefit greatly by simply sitting on the floor for as long as she can every day. In time, add the reclining twist and then Bananasana, so that the spine is being moved in all 6 of its degrees of freedom.
After any exercise and for the next 24 hours, she should be very alert to how she feels. If she feels this worsened the problem, she should go even gentler.
I hope this helps!