What is she spending the cash on? It could well be poor money management as well as low income.
I had a relative who did this - constantly 'borrowed' money and never bloody gave it back. I cringe when I think how much I gave. It got to the point where it was constant.
In the end, hard as it was, I stopped doing it. I didn't want to see them without essential items so if they askes, I would offer help in other ways e.g. they would text and say 'can you lend me £10 so I can buy something for tea' and my reply would go something like 'sorry, I don't have any money to lend but I do have x/y/z in the freezer/cupboard so I could give you that?'.
The thing that got me is that thr reply would usually come back 'oh, no, it's ok, we'll sort something'. Made me realise that it was poor money management and wanting to buy non essentials like a bottle of wine.
Others in the family did the same and eventually, the person stopped asking and had to start budeting properly like everyone else.
Offer help (if you can) with cooking a few meals for the freezer, helping plan a budget etc. but stop giving cash.