I had a very similar thing happen in front of my eyes. A young mom with her two little kids was at the check-out in the Dollar Store. She was buying food items for the kid's lunch. Of all the crazy things, the credit card machine suddenly broke; you could only pay in cash. Of course she had no cash and the girl at the register just stared at her. I looked over and said, "it's paid for" and gave the clerk the cash to pay for the kid's food. It couldn't have been more than $5 but to that mom it was a fortune.
Sometimes you just help.
I bought groceries for a woman that I work with. Her husband had lost his job, unemployment had been denied, they'd already been to the food bank and there is a limit on how often you can go. She and I make peanuts, so her paycheck wasn't much help.
I took my 11 year old with me and he whined and complained a lot at first. As I talked to him about their situation he got a little more enthusiastic. Then he got the job of ringing the doorbell and running like heck after we'd snuck the groceries onto the porch.
As we were driving away he said, "I actually feel a little warm inside." So, it was good all around, and I found out yesterday the husband has a new job.