On reading the story from both the OP's link and the news story that in turn links to, I can't see any mention that any of the other kids
They merely state that people got out of the car and left it to the next person to make their own decision to get into the driver's seat. The easiest thing to do with the keys is leave them in the ignition, either with the motor either still running or turned off.
I've switched drivers in rest areas and hotel parking lots more times than I care to remember back in my days of driving charter buses up and down the east coast. Never once did we switch off the motor and hand the keys to the next driver, we left it running every single time.
The ONLY thing any of us here have to go on is what is written in the story. It doesn't mention handing the keys to anyone, doesn't mention that one time. In fact the logistics of trying to operate a motor vehicle when drunk would suggest they'd leave the keys in the ignition simply so the next person wouldn't need the complicated (when impaired) fine motor skills of inserting them again.
With that all pointed out, yes they're all stupid for driving in that condition but the ultimate responsibility for her actions lies with the deceased individual herself. If she needed her friends to tell her she's incapable of making the rational decision not to drive then those friends, who were quite probably just as drunk, would need someone else's help to make the decision to tell her that she's too drunk.
There is a difference between the suggested positive action of physically handing over the keys and the passive action of merely vacating the driver's seat and leaving it available for someone else to make their own choice.
They're all stupid, they've all got to live with the knowledge their friend died after they left her, BUT she was the one who decided to drink, she was the one who decided to drive, ultimately the responsibility is her own