My theory on the ending...(spoilers)
I think that Kelly had actually died of a heroin overdose and that when she was wandering round outside, that was her trying to find the afterlife and be at rest. It took her a while, but by the time she got there, her friends and family had all passed too and Lol was waiting for her to welcome her in. What we see is her finally being with everyone at the end and being at rest.
OOM POM PAH OOM POM PAH thats how it goes...