Random Acts of Kindness - Can they offend?

I was in Asda after work today, with my partner, and casually doing our shopping, and in front of us there was a biggish girl/woman, not huge, but what made her really noticeable was her huge afro type hair, and she was white, childishly I pointed her out discretely to my partner, who after we had walked past her, put me on a huge guilt trip, and rightfully so.

As we walked past, we overheard her saying, as she slowly walked back from the bakery area;
"If we want some bread for the ducks, we need to come back at around 7pm"

On reflection, after digesting what she said, I looked over and noticed she was with two very elderly people, and the guilt came across me massively, my partner really enhancing the guilt, making various serious suggestions about the situation this group of people could be in, such as the bread could be for them, as it is all they could afford, the girl no matter how her appearance was in fact a lovely person and genuinely for the ducks, and various others.

I suggested, as I felt guilt, and to be honest still do, that I could go over and offer to buy a token amount of bread for the ducks, say five or ten pounds worth. It was argued by my partner that they may find this offensive, and reluctantly I agreed, and the last thing I wanted to do was offend the girl and the people she was with.

Would you be offended if a random passerby had heard you were after some bread for the ducks, and offered to pay for some bread?

I ask, as I feel bad still, and would love to of made it up somehow.

I was tempted to pop the money in a charity box, but its not normally something I always agree with, as the money often gets syphoned to admin etc of the charity, I am one of these people that if I was going to donate, I would like to do it so I know it has gone straight to a good cause. For example, this girl with £10 could of got some bread for the ducks, and a nice desert for her and her 2 elderly friends, and it would of made them happy for a night at least.