I am, an acupuncture practitioner, I have had many of clients, who has been helped with electro acupuncture,check one near you.
Good luck
Presumeably she has had a laminectomy. The dropped foot can be due to nerve damege or temporary nerve impingement. Unfortunately, "drop foot" is often permamanet after a laminectomy. Not always, though. A wedge of cartilige had been removed from between the verterbra, and the weight of her body impinges on the nerve. There is some evidence that maintinging good hydration (eight - ten glasses of water a day) will provide additional strength to the remaining body of cartilige (which is primarily water). There are also a series of physician excercises that can only be taught in person by a trained professional. The money will be well spent. Often a short period of anti-infammatories can do a great deal of good, as well as hot and cold baths. Three-five days of prednisone is a common prescription, followed by a week or two of motrin.
There are no vitamins or supplements that will cause nerves to regenerate. Since the doc said that the nerves are not damaged, you may wish to check out other conditions that result in foot drop. Massage and muscle exercises should be done to prevent muscle atrophy from lack of use. If the foot begins to feel cool to the touch when compared to the other one, get checked out for circulation problems. Good luck