OP I sympathise because neighbors causing stress can be awful.
Before now DH and I moved into together, I had my own place. It was a flat above another flat.
The lady downstairs was abusive from the day I moved in, literally coming charging over to the front gate as I was moving boxes in, asking who the eff I was and saying she had "told" the council her granddaughter was moving in upstairs. I tried to politely say my flat was not council but private rent but she called me a liar. She then started taking stuff off my balcony and bringing it back downstairs as I moved bits in bit by bit.
I had to call the police as a simple hour of moving in as I didn't have much stuff went on for near on two and a half hours with her shouting abuse. Police came, said she was calm now and granddaughter was on her way.
The granddaughter was a spoiled little cow and on a par with her gran. I thought she was coming to apologise. She was coming to tell me off for upsetting her poor old granny and demanded to know why I had "grassed her up". I shut the door on her
For the two years I lived there, it was a nightmare. A living hell. I had police turn up weekly, accusing me variously of drug dealing, burglary, being a prostitute, and having loud parties and fights in the flat and garden. All of it was rubbish. I actually had to contact the police complaints commission as it became harassment and police fell for it each time. Some would be very embarrassed, a few were downright rude, suggesting I had got rid of evidence and no smoke without fire.
The final straw was when I was away all weekend and my flat got broken into. Her granddaughter said, as I waited for police "oh dear, did someone rob you?" She laughed. I could never prove it but I'm convinced it was to do with her.
My landlord was sympathetic but said he couldn't do much as the flat below was a council flat. Council was useless. I wasn't their tenant so tough luck.
The final straw was when the gran got herself a fella. He was abusive as hell. Used to roar at me for being loud and upsetting his princess. It was farcical.
I was coming home from work, it was dark and he flew out the front door, her close behind shouting that I had flooded her flat. I ran up the stairs to my flat with them following me and just got the door shut. He started kicking and hammering on it. I was in tears. I shut myself in my bathroom.
I called DH (DP as he was then) and he jumped in his car and drove straight over. The neighbors had gone back downstairs by this time, DH rang to be let in and that's when I felt safe to leave my bathroom.
He went back downstairs and asked what this leak was about. Apparently they said my washing machine had done it and had been leaking for months. First I'd heard of it
So DH goes up to my flat, pulls the washer out, bone dry. Not a drip. No moisture at all. He demands the man downstairs comes up, he didn't even apologise.
Then the police turned up as another neighbour heard the banging and I think was worried for me.
The police's attitude? After a year and a bit of coming to bitch at me at her request, never finding anything to be there for?
"Well you shouldn't wind her up then"
That evening I told my landlord I'm going, I moved into DHs flat and the landlord let me off my notice. I had lost 2 stone with stress.
All I can suggest is if she turns up, and as her story has already changed, record her with your phone. That way you can prove she's lying. I would agree about raising a concern via adult social care. It's your home and she has no right to demand money or threaten about her family.
I bet her family are as bad. Cough up? Who on earth does she think she is