Seems this story of the homeless man giving this lady some money for petrol when she ran out was just a total scam, by the homeless man and the woman and her partner who have now been arrested.
https://www.bbc.co.uk/news/world-us-canada-46221766
But thousands of gullible people came forward and pledged over £300,000.
So note these "Just Giving" type web sites are totally unregulated and there is no proof that the money is EVER going to be given to the "deserving" person (or if the deserving person even exists or has the illness or problem that the Just Giving page describes).
So think carefully before being another victim of this type of scam.
Note that scams come in many forms and the internet has given people the ability to run scams on a large scale.
So think TWICE, or even THREE TIMES, before giving ANYONE your money.