When I learned in Mayrhofen, the Spiess Skischool was the only one and was widely regarded as the best there was.Anywhere. Unfortunately it is no longer there.
There are now four to choose from - SMT, Die Roten Profis, Mayrhofen 3000 and Skischool Mt. Everest (Peter Habeler.)
The only one I have experience of is SMT (Schiscule Mayrhofen Tirol)My partner, a very nervous skier, has had lessons from 3 of their instructors and found them all to be very good indeed - patient, thorough and humorous.
A couple of years ago I had a 2 hour private lesson with one of them (Marcus) and it was fantastic - I had to ski really hard and it was loads of fun as well.
SMT is run by a guy called Max who was formerly employed by Spiess and of the older instructors who are still around, most of them work for SMT too.
I don't think you could go wrong by choosing them, but check out whether they have classes on the recently expanded Ahorn area first, where the skiing may suit your wife a little better.
Feel free to pm me if you want to.
Skidaddle.
