My parents also were credit-averse for most of their lives. In their retirement years, Mom got a couple of credit cards without really understanding credit and went on shopping spree's with dementia and early Alzheimer's. Once I got involved with their affairs, it was one more thing I had to straighten out for them. I mention this because there is a potential risk and burden to family members if credit accounts are kept and used, especially if dementia develops. In the context of the situation, your Mom's decision seems it could be a prudent and considerate move, depending on her overall health, age, and finances.
Ironically, I've been adding credit and improved cards in my latter working years so that I will have great cards and limits in retirement for travel and other spending after my income declines. But this is a good reminder that, at some point, unwinding all those cards and limits might be the wise thing to do.
I agree with @M_Smart007 above, though, that keeping at least one card open might be a good call. Credit cards are just one more tool to have in managing our finances. It's easier to keep an open card than to have to apply for a new one if she needs or wants it again. As long as she is disciplined about the usage and it's not a threat to her budget, keeping a single card open would be little to maintain and would give her options.
