Using a post office may become as difficult as finding an ATM, so do not be so sure that your mum, or her representatives, will not have to use a bank eventually.
There has been a widespread report recently that more than 2,500 post offices could shut in the near future:
This is just one of the news reports:
https://www.express.co.uk/finance/city/1129571/post-office-closures-latest-list-is-my-post-office-shutting-downThe post office itself is apparently on the brink of collapse and indeed I can vouch for that in our town; one sub-post office and one main office has closed over the last few months. The business has been hit by changing customer practices, like using the online facility for renewing passports, obtaining road tax, managing bank accounts, paying utility bills, etc, etc.
Once again, it must be said, that the retail sector is changing fast and post offices, like branches of the main banks, are disappearing as most of us use the modern facilities. I include myself in that, getting my pensions into my bank account and paying everything via standing orders of direct debits or using a debit card. I cannot remember when I last used a post office; I even buy the few postage stamps I need over the year in Sainsbury's!
This is not good for the elderly who have not adopted the new fangled ways of business, but that is the way life is going in 2019