My ER had a live-in carer just after her husband died. She didn't really need it then.
The deal-breaker came quite soon - the carer didn't like cats, so not only were there ructions when she caught the cat napping on her bed, worse still... She stamped her foot, the cat ran off, and she laughed.
As you can imagine, she was gone within the cancellation/cooling off period.
The thing to consider is... Well, this is what I've seen with my ER. The carers she gets on best with are the more experienced (usually, older) ones. And they're the ones who, quite understandably, have a life and a family and want to sleep in their own bed at night!
They aren't usually the ones available for live-in care.
My ER's care needs now (pretty much bedbound) are such that we would be looking at a nice care home for her discharge, if money was a concern. If you get past 4x care visits a day, it's normally cheaper to be in a care home.
However: she's not suffering from confusion. Any overnight care would be to provide reassurance and help with the commode.
She's not going to be, say, sneaking down the road after dark and hiding from the frantically searching carer (who she believes is poisoning her).
Care homes are usually built to make "wandering" difficult.
The other thing with live-in care, is, if all the carers - and there won't be many - are great, happy days. But you are literally living with them, and if you don't get along, it's not like a care home, where you may find Carer X winds you up ... but she only works so many hours, goes home after her shift, and you can usually ask for another carer if you really don't get on.
Very long way of saying, it sounds like a care home - for "respite" at least to start with - may be the least worst option for your Mum. But it is a very individual decision.