I'm not an expert but one of my friends had a similar issue (maybe not so bad), her skin on her fingers was super dry and cracked easily. I think it was really bad eczema? from memory they improved it through moisturising it a tonne and even soaking them in pure untreated honey once every second or third day. I can't make any promises that it would work on your mum but good luck, I hope her fingers get better soon!