Hi there! I have a lot of experience with this problem. I have had hairloss for a long time and I have read many articles on the subject. First of all there is really only one approved treatment for women's hairloss and that is Rogaine. A generic brand is available that is cheaper than the actual Rogaine. It is the same formula just alot cheaper. However your wife will experience more hairloss at first and then it may cause some growth but it must be used continously. If she stops the hairloss will return. Anything else is pretty much a gimmick.
I have a few suggestions for you as well medically. It is possible that your wife may suffer from an iron deficiency and that will cause hairloss. She should get her level checked if this hasn't been done already. Thyroid problems can also contribute to hairloss. Get this checked as well. Stress is another problem. Hormones too. As women age their estrogen levels drop and this can cause hairloss. Also a poor diet can contribute to hairloss as well as extreme diets.
I wish you alot of luck and I hope that I have helped you both a little. Think it's great that you want to help your wife