DISCLAIMER - PLEASE NOTE:
Another one of those Long Post that might not interest anyone, but who it is intended for even though the information is relevant for some too and there are No Smilies either . . . Just Sayin' . . .
@ "liblue" - Just read your post . . .
AND - Although "You" have gotten some really great advice from others already concerning this subject - here are "My" thoughts . . .
First - IMO -
YES - DO NOT APPROACH this person alone, especially if "You" feel at all vulnerable ! ! !
WOW - I feel so sorry for "You" to be in this type of position . . . In addition to the fact, that I am feeling sorry for this individual too . .. Especially since from what you mentioned in your post - He was in "Rehab" (be it for any number of reasons - Physical/Alcohol/Drugs) and that he gets very few visitors (who BTW from your description are actually Home Healthcare Attendants) . . .
I can also tell from what you mentioned, that it seems as though He is going through a lot of "Stuff" be it of his own choosing or not . . . Not only is it possible that he is alone, lonely, and feeling a lot of pain - but he has no one else to turn too and could already be "brushed" off by a number of people, including any Family/Friends he may have and/or have left - nor those who are supposed to help him like his Case Manager, Social Worker, Doctor/s, etc. too . . . In addition, whatever else he is going through - it seems as though extreme depression could have set-in also . . . Which leads to the fact that many people in this same position have taken to start smoking even more then they have before (be it tobacco/drug related substances), especially since they are in a since "Self-medicating" with the MAOI's
( Monoamine oxidase inhibitor - Wikipedia, the free encyclopedia ) that are found in these substances . . .
Now I am NOT suggesting that "YOU" need to get involved and it is not something, especially being a single woman living by yourself should or need to do . . .
But this person needs help in more way then one - especially since money probably has nothing to to do with the fact that when you are addicted (be it Tobacco/Alcohol/Drugs) you will always find the money for that addiction before basic living necessities . . .
So if possible and only if you feel like doing it - I will send "You" a couple of disposable (1 - NJOy

& 2 - "SmokeSticks" Regular "Tobacco" & "Cappuccino") that I got for a situation just like this - SO
PM "Me". . .
AND - Then when you get them, either - 1) maybe "You" (with someone else - maybe one of the "Home Healthcare Attendants along) can go to him and even say that "You" are not complaining - But that as a neighbor
"You" are only concerned about his wellbeing and/or worried about Him
because "You" can hear him struggling being up all night and smell the smoke coming from his apartment - SO since
you also had a problem Quiting Smoking until you got an "eCig" - "You" got these for him to try . . . or 2) If You can trust them - casually meet up with one of the Home Healthcare Attendants and give the disposables to one of them to hand over to the neighbor . . . or 3) Write a note saying the same thing and then leave them in his mailbox or taped on his door . . .
Just a thought and hopefully one of these suggestions are helpful . . .