Keep the money or get it back to her somehow

[RockSocks]

So there is an old lady who is very taken with my dog
She is so fond of her that she says she's her dog
I know she lives alone after her husband passed and she has limited mobility so when we're out I always cross over to say hi and let her have a snuggle as she's a sweet lady and it seems to make her day as she misses her dogs so much and can't have more, I don't mind doing this and am happy to continue

The problem is today she gave me £5 to treat Sock to something
I couldn't get her to take it back she was in near tears till I agreed to get her a new toy/treat's with it

Do i just accept it and hope its a one off?
I'm tempted to try and find family of hers and get it back to her, its a small village so should be easy, I don't want to offend her but know how hard it can be financially at the moment

Also I don't want it becoming a habit we see her out and about once or twice a week and I worry she might continue

Why not, just for this first time, buy your dog something with the money, take a photo of him with his new toy, wearing his new coat or whatever, put it in a frame and give it to your neighbour along with a small bunch of flowers as a thank you from your dog?
if she does try again then you could go down the ‘ he doesn’t need any more toys, he’s getting fat, so cutting down on treats ‘ route.