If I've had the money, I had friends who claimed to have nothing. One would message me saying, oh it's so cold, or the electricity had gone out, or that she was starving. I'd hand over £50 at a time. She also didn't have a car so struggled to get about, so I gave her a loan of £1000+ to get a cheap runaround, plus tax & insurance. This was years ago, I remember my hubby saying she & a couple of others were abusing my kindness. Never saw the £1000+ again, but part of me never expected to.
Same with another friend, would always expect to go fancy places but could never pay. She always chose the most expensive thing on the menu. She even coerced me to clean my wardrobe as my clothes were Mumsy, but I had children, so Mumsy was what I was. As we were clearing stuff there was a pile she was going to take & a pile for charity shops that wasn't as big.
It was the same with family too, if they needed money & I had it, I'd happily help.
I don't think any ever paid back. When it was decided I'd stay at home to look after DC, I didn't have the money to give, so the best friend who professed I was like a sister stopped talking as I couldn't ask my husband to help her out.
It's wise advice looking back I was giving the money, if I couldn't afford to then I shouldn't, as it doesn't half feel awkward try to ask about it. That was the case with some furniture when we moved house, my husband wanted something say half of what I said she could have it for. I never got my share but my husband was on at me to get his, as he had things he wanted to buy, he wasn't keen on the colour scheme.
You can get friends who wouldn't dream of short changing you, or you can get friends who borrow more than they can afford, so you'll get it drip fed almost as & when they can afford it.
If my first friend really didn't have gas / electric / food as she said, which my hubby doubts as when baby 3 came along it was all organic baby grows, then I'd have felt guilty leaving her like that. There's no way of really proving it. You just trust people are being honest.
I'd say with ref to the £100, if you lend money you can't dictate what it's spent on. But you could say look I can only afford £50 will that be ok. Don't dictate to her that she should cut her coat according to her cloth, otherwise you could lose that friendship. Just give what you think is reasonable.