Kirsten - I remember you saying, before you went into hospital, that you didn't really have any friends to look after your girls. You said something about your increasing poor health having contributed to that.

It sounds like your neighbour is experiencing the same thing - maybe a different illness, but an illness nonetheless.

Perhaps she has lost friends also, because of her moods, which she needs professional treatment to help.

Rather than fear, perhaps reaching out to her with some understanding would help.

Something like a little card showing you understand: "I remember when we had a good friendship and enjoyed knowing each other. As you know, I have been unwell, and had to go away for treatment.
When I got back, I heard you were in hospital. I hope you feel better soon."

Not exactly those words - just identifying with her situation as much as you can because of what you have experienced. Perhaps that will help the fear.

Just my sense of it - people are not the danger here; fear is.

{{{{hugs}}}}