Please help me

So yesterday at around 4pm I was just chilling in my room when my cousins (F15) calls me. Just for clarity we DO NOT have the best relationship and I barely see her save for Christmas and thanksgiving. Curious I answer and she tells me that she’s in a city an hour and a half away with some girl. I asked her what she was doing there and she said she was stranded there. I told her I’d come get her so I drive up there and she’s in a run down trailer park in some sketchy single wide. I walk up to the door and they practically slam the door behind them so I can’t see inside. Keep in mind I am 21 years old and did bring my pistol just to be safe. But I get them safely in the car and they REEK of weed and just general nasty smells. They mumble thank you and just pass out in the back of my car. I end up bringing them to her dad’s house. She told me not to tell anyone but I feel I have to. I’m just worried if I do I’ll be throwing away the trust that she can call me if she’s in trouble. What do you think I should do? She’s only a freshman in highschool and her mom is a meth head on her death bed. I just don’t want her to end up like her mom.