Not sure what to do about Neighbour

[Whenwillthewashingend]

We've been in our home for 18 years, and since almost day one we've had problems with our elderly neighbour.
She has a mental illness, and have had many accusations thrown at us, from gassing her out, to working for the mafia, and leaving a dead cat in her garden. She has periods of banging on the wall, and my mental health is screwed. I have anxiety through it all.
She has no family, and gets no visitors. When we contact 101 about her, she gets a visit, then nothing.
All that aside, she is now in her 90's, and I'm feeling sorry for her in this crisis.
I don't want to knock on her door, because it will set her off again. She hates our family, even though we genuinely don't do anything to her. We try and live as if she doesn't exist.
I've got a click and collect booked tomorrow, and have added some bits, with her in mind. Loo roll, bread, milk, etc, but I don't want to physically hand it over.
I thought about leaving it on her door step at night, but am worried with her paranoia, whether this will set her off.
I just don't know what to do for the best.
Sorry for the length.

Around here,the local vicar would be someone to talk to about a situation like this.

We live on a housing estate, and no local churches, but that is actually a really good idea. I know a minister from a church in another area, and don't know why I didn't think to talk to him.
Thank you.

Maybe contact Age U.K., or help the aged.

Do you know if she has any support for her mental illness?

I'd call the local council to make sure she's on social services' radar. I'd leave the stuff on her doorstep, with a note, perhaps anonymous. Is there another neighbour who has a less difficult relationship with her?

Well done for looking out for her.

As fair as I'm aware, she doesn't have any help. The local pcso's are aware of her, but when I've spoken to them, she refuses any help, and there's nothing more they can do.
It's so sad, because in the past, I would have loved to have done things to help her, but it's just not worth the stress, for my own mental health.
Thank you for your suggestions. I genuinely feel better about the situation now.
It's funny how a stranger can give a solution to something that myself and my husband have been worrying about.
Ive got bread, whole milk, margarine, jam, soups, cup a soups, toilet roll, and a packet of biscuits on my list. If anyone could suggest something else, I would be very grateful.

What a lovely, thoughtful neighbour you are. That's so very kind of you, especially given the trouble she has caused you.

My late Mother in law had a mental illness, so I know it's not totally black and white.
I still wouldn't talk to me my neighbour. I'm not that nice.

That's really lovely of you OP. If you don't want to leave it on the doorstep you could pop a note through explaining that you have extra stuff and if she wants it then she can put a note back and then you will leave it outside and ring the bell or something - I'm wondering if this will cause her less stress than leaving the food but I really don't know.