The best advice you can give to a woman who is suffering with female pattern hair loss is to seek the help of a doctor who specializes in treating hair loss. For women, determining the cause is not as straight forward as it is for men. This is a problem because determining the cause is the most important part of determining the best treatment.
Refer her to this link:
If the cause is in fact hereditary hair loss, I suppose you could possibly say that the "Big 3" for women could be Spironolactone, Minoxidil and Ketoconazole. Those are the medications I use along with my laser comb.
Spiro is a blood pressure medication that can be used as an anti-androgen to block reception of androgens including DHT.