I asked her previously if she would like us both to go through some stuff to get rid of anything This is very well intentioned, but not where to start unless someone has specifically said they want to get rid of stuff (even then it’s unlikely to get far if they haven’t done the ground work first)
The groundwork is the changing of mindsets. (even those desperate for change rarely get changed by being told ‘you don’t need it,’ or ‘why do you need it?’) It’s a light touch, quite complicated process, covering the various beliefs going on in that individual and their circumstances, and can only really start when the person has at least a sense of wanting change and is prepared to co-operate with mental exercises.
(Anything else is generally like trying to ‘fix’ anorexia, by just making the person eat.)
I suspect it’s as good as impossible for an adult child who’s had a traumatic upbringing and relationship, to accomplish, no matter how good or patient they are. There has to be total neutrality, and an inability for the sufferer to wound the person assisting, (preferably visa-versa too) pretty impossible when there’s been a prior power balance, let alone abusive situations which it sounds like yours has.
The stuff may well make her feel comfortable, including even if she hates it.
It is a mh issue, often connected to deep seated hidden trauma, and one I’ve battled a long time, full of contradictions, and cul de sacs, and it attracts a lot of hatred, self-loathing, and shame.
Damaged people can be very extreme characters and your mum sounds as if she fits that stereotype, but lots of us are terribly normal, just double whammied suffering a condition we never asked for as a response to trauma we never asked for either!
It's when everythings untreated long enough, we respond with symptoms that force us to stop pretending all's OK. Many of us then hide our symptoms and selves.
Animal hoarders do the opposite, creating situations where others will take notice.
Your mum and you are probably at a point where there’s little to be gained from trying to change much, but I absolutely agree that you can’t be party to animal hoarding, but you also don’t want to find yourself accused of withholding her money if she’s deemed competent.
If you can't find easy documentation, I hope you will consider using the exceptional payment service to free yourself swiftly from financial entanglement, it will protect you, and the part of the relationship you sound like you want to keep, and is simple and instant.
You can then go through whatever length of time it takes to open her a bank account. Transferring to bank payments is simple, they do it all for you when given an account number.