Read Dr. Timothy McCall's response:
In general in yoga and yoga therapy, we teach to the students in front of us, not to their diagnoses. So if your student is generally fit, she should be able to do a good, well-rounded practice consisting of all major types of asana (forward bends, backbends, twists, inversions, and so on). If she is open to them, other practices such as chanting, Pranayama, and meditation can be helpful in dealing with stress and fatigue and as long-term preventive medicine.
I think it would be also extremely useful for this student to start to learn restorative yoga for those days when she is too tired, dealing with medication side effects, or otherwise unable to do her normal practice. Finally, since heat can interfere with nerve conduction, a problem area in MS, I would recommend that she avoid overheating.