I started getting them last summer... and let me tell you, you want to be careful with that. I now have permanent inner ear damage because my tube-thingy has a kink in it.
My doc told me the following:
1. Get ears cleaned out before a dive trip. This means going to the doctor and having them pour gunk in my ear. But afterwards, my ears feel all clean, so that's nice.
2. Get ear drops, the medicated kind that require a prescription. Take them on all dive trips, and use them as a preventative.
3. Take allergy medicine, and drink lots and lots of water. This will keep the mucus at bay. Somewhat.
Finally, ascend slowly and with lots of reserve air. Your wife may have to descend a little, then try to ascend again, until her ears clear. Also, rub behind and just below the ears while she descends and again while she ascends. I learned this from a diver, and it really does help.
I hope this helps! I know that many of the things I wrote have to do with outer ear infections. However, my doc said that many times that's why reverse ear blocks occur, although I don't understand why.