From my experience in nursing/care homes this isn't just a phenomenon restricted to people with AZ or dementia. ALOT of people, even some not considered to be very old obsess about money. I think part of it at least is they have insight into the fact their mental capacity is deteriorating and the read and hear about financial abuse all the time. It makes them very fearful. Heck it makes ME very fearful of being ripped off, so MAGNIFIED is definately the right word.
Try to make sure her bills are on DD and make sure her bank statements are easy to read. Some banks might even be able to help with this. Someone she trusts could write a sort of permanant list of incomings and outgoings for her to refer to. Copy it and laminate it and let her put one near the phone and in her handbag. Give her a money bank with a "see through" front to keep her coins in. Ask her if she would like a set time every week for a person she trusts to be her "accountant" and check all her bills and statements are in order. Give her a folder to keep receipts in and write very clearly at the top of each one what they are for.
Sometimes distraction works. Is there anything she can be diverted with to take her mind off her finances?
I do sympathise with you. Im sure you know its only her illness that makes her so oblivious to your kindness and patience, but when you work so hard for her happiness it can be really hurtful to be acused or simply ignored. Try not to take it personally.
I've found that, although it can take a long time, the worse the condition gets the less notice is taken of money, perhaps because they can't remember or feel too tired to bother. It could be feelings of uncertainty about paying for her future that are promoting these thoughts. Is she clear how she will be looked after, and how her finances will be dealt with once she is no longer capable? Has she got something in writing? Is it repeated to reassure her? Maybe she could speak to a solicitor to have her wishes discussed.
Good luck and keep smiling. It sounds as though you are All doing a great job.
Edit: Ishard, I think you should get an LPA set up for yourself now.before you start trying to pay for things with your library card and getting cash out with your BlockBuster card!!!! ehehehe