I don't work in finance so I'd better not say too much but the mortgage is a secured loan and credit cards arent, and different companies will have different policies anyway. I don't think there is necessarily an industry standard as these are completely different types of ' debt'. I would have thought that the mortgage needs to be redeemed as soon as possible either by selling the property and paying it off or if the property is inherited by someone then they may have the option of taking on the loan as well.
I would also check whether your friend had any life cover or insurance that meant that the debt itself was cancelled on death. We have that sort of cover and its quite common.