I was hit up by a guy once for some money to buy some soap so he could wash up and get a job, I opened the trunk and handed him a bar of Ivory out of my BOB and he looked at me like I'd spit in his hand. I offered him a towel too, but he was already heading off.And yes. I do know.
I deleted the rest.
All I can say is unless your willing to give such a person a reason to not want to die then hard as it is there's little you can do.
Donate to your local church. Mine has a wonderful outreach program and is filled with people best prepared to help the truly far gone.
At most, give them food.
Never, never, ever give pan handlers you suspect have addiction issues money. Your only enabling them with money.