I know that U.S. Customs will not let you bring meat products into the U.S.
We're spending the month of September touring France, Germany, and the Benelux countries.

My wife is still nervous about Hoof and Mouth, and Mad Cow disease. Does anyone know if she would be prevented from bringing Beef Jerky from the U.S. into those countries?

I have returned to ZRH yesterday from SFO bringing along a huge bag of Beef Jerky. No questions asked, no inspections - just fine. And that's how it is in most European countries. I saw some signs in April saying "No meat from the UK please", but since you'd bring it from the US it would not affect you.