I'm new to this site as my father was just diagnosed 10 days ago with PC. He was given the option of Whipple IF the cardiologist and pulmonologist gave him the green light. He has extensive other problems including kidney failure (his is on renal dialysis 3X a week), congestive heart failure, and diabetes for which he takes insulin. He has opted NOT to do the whipple but to try the Cyber Knife instead. For him, we were concerned that the recovery time and chance of infection following the surgery were not worth it. He takes forever to heal due to the diabetes.
I think you have to weigh the benefits with the possible side effects. I wish you and your mother all the best with this decision. It is certainly not an easy one. I'm not sure if we/he made the right choice, but it seems to be the best one for him. His quality of life seemed more important for the time he has remaining.