Could my wifes klonopin, (clonazepam) wygesic cause her BP to drop?

Most Definately. Cardiovascular side effects of wygesic (propoxyphene) have included arrhythmia, bradycardia, cardiac/respiratory arrest, congestive heart failure, tachycardia, myocardial infarction, hypotension, decreased blood pressure, elevated heart rate, abnormal heart rate, and dizziness. Combining with Klonopin (clonazepam) can enhance many of these side effects and is not recommended. Contact md for evaluation asap.
Yes. The combined effects of Propoxyphene (the active ingredient in wygesic) and sedatives can be dangerous, and even fatal. In a large canadian study Propoxyphene use alone resulted in a 60% increased risk of hip fracture in the elderly. It also inhibits enzymes that can increase concentrations of many psychotropic agents such as tricyclics, phenobarbital, sris, and others.