was she trying to kill herself in the end?
In the end, my impression was she gave up. She told her boss she would not be coming to work, because she realized she could not keep the job because of her bad conscience (stabbing her only friend in the back). And she was just tired of running and taking care of her alcoholic mom and hustling for money or jobs etc. So she tried to go to sleep with the gas on (that would explain why she made sure to put the towel underneath the door to block any air coming in). But she ran out of gas that 's why she went to purchase the other tank of gas. Poor thing, even when she is trying to kill herself, she has to pay and then carry that heavy thing. I would like to think that the helping hand of her forgiving friend at the end is an indication she did not go through with it. If I completely misread this, can anyone else offer their interpretations of the ending.
By the way, I loved this movie. The irony of the trailer park being called "Grand Canyon." The horrors of bureaucracy: She can't get unemployment because she hasn't worked long enough. She can't get a job because they only hire long term unemployed. The whole thing was very moving and disturbing.