My late mum had really dry skin - she used to get huge tubs of E45 and slather it on. I think in the end the GP was giving it to her on prescription. Her skin was very fragile (she believed due to years of steriod use) so she did anything she could to moisturise it, but she shed dry skin ever such a lot.
My mum was that age, she had very flaky dry skin, almost papery and very thin, there is a mousuriser, think Boots sell it nowadays, it's called 'Double Base' It's brilliant, so much moisture, sure it would be great for her!......................
Another good product for dry skin is DiproBase and you can buy it over the counter. my doctor gave it to me after I'd had radiotherapy on my throat and I have continued to use it ever since.
I have lizard legs and have just started using the skin so soft range from Avon..its on bogoff atm and free postage and packing if you spend more than 20 quid, both website offers. I have been using it one week and already notice a difference....a bonus is that the dry oil spray also seem so repel mozzies.
Internally I believe that evening primrose oil capsules can help, currently 3 for 2 at tesco.
(I have no financial or other interest in either company btw)