Hi and welcome to the Forum. What you are describing in your mother sounds very like GSM (genitourinary syndrome of menopause), often called VA (vaginal atrophy). It is very, very common in older women and is due to lack of oestrogen. There are plenty of threads on here about this, and you can also look it up on the main index.
The cream your mum has been given is probably Ovestin. She should insert this with the applicator every night for two weeks, and then use two or three times a week thereafter. If she doesn't like the cream ( a bit messy and some find it irritating) she could ask for Vagifem instead, which are tiny pessaries.
Please try not to worry, I know that's easier said than done! She is about the same age as I was (67) when VA first struck. It can certainly be controlled and will improve, but treatment has to be kept up forever.
Best wishes,
JP x