elderly mum who needs help

I agree with Eloethan.
She obviously needs help.

I don't understand what you think she's doing wrong

I am a bit confused by this. Are you saying your mother shouldn't have these people in her home? You say she has just come out of hospital - again - so surely she needs this sort of support? Neither you nor your sister is near enough to help so I don't understand what the problem is.

How often do you normally visit? Do you speak on the phone? How does your sister manage this situation?
If you know she is being cared for I would just do what you normally do,or even stop doing that and see how it feels.

I don't think there is anything you can do, except be thankful there are people there to help her. You are too far away to give daily help. Presumably she's had her vaccine and soon will have another, and we all have to get back to some sort of normality when vaccinated.

Jaxjacky - Her neighbour is her support bubble and shops for her, puts her bin out, deals with the cat tray and keeps her company!

Explain to her if you can, but if she’s insist then there’s not much you can do except let her know that and disengage.

I think the cleaner and carer are ok, what would the neighbour be doing?