Why do you hang out with people you don't like very much in first place? She was your dog walker, not your sister. There's nothing wrong with keeping relationships professional.

Tell her that you can't and don't be sorry about it.

You could give (rather than “lend” as she will probably never pay you back) her $100 for old time’s sake just to make you feel better, but deep down you know this is sketchy and she had bad judgment.

About 10 years ago we hired a dog walker. My dogs adored her. Aside from the scheduled walks she used to call me up and see if I wanted to take the dogs out on the trail for a walk and we used to do that together every one in a while. So we had a sort of friendship. But she was not someone I really liked very much. She talked a lot and didn't listen. She had bad judgment. She just..wasn't a friend friend. But I had the sense I was once of her only real social contacts.

She kind of fell off the face of the earth during the pandemic for various reasons. She stopped walking dogs. We rarely saw her. We exchanged emails every once in while. In the last year she started emailing us to ask us to borrow money related to her house. She owns her own home. The amounts of money are pretty big, like over $1K. They always have to do with what seems like her getting ripped off by a contractor. A plumber, an electrician who, it seems to us, needs an exorbitant fee from her just to start work or to continue work. We respond by warning her it sounds like a scheme. But she doesn't listen. We don't lend her money.

At this point I don't respond at all to these emails. But I feel guilty.