The fact that not one person in the group (what kind of group was this?, any experienced hikers or was this just a group of ordinary, non-hiking folk?), knew how to deal with it, let alone prevent it. Why couldn’t they reach her until the next day?
My guess is it is likely to be a DIY hiking group that wasn't aware of the the extreme conditions that can happen in the canyon and were totally unprepared.
Have you ever been to the Grand Canyon or into the canyon? I remember the ranger telling us that she got really mad at people she saw trotting down into the canyon obviously unprepared, but it was going to take her and the other rangers most of the day to carry the body back up.
People don’t realize how dangerous it is…a couple of years ago, a doctor died of hyperthermia and dehydration because she went into the canyon with only a small bottle of water and couldn’t make it back up. Her friend couldn’t carry her out, there’s no cell phone reception from most places in the bottom, and even so it takes hours to get down there and back.
If you’re dehydrated, you start to throw up (you can’t keep down water if given orally), collapse, get delirious, your brain swells and you go into a coma and die. You need IV electrolytes immediately, among other things, and most hikers unless they happen to be combat medics are not equipped for it.
Just very sad, people don’t realize how risky it is. Plus the Grand Canyon has an elevation of around 6,000 ft, and this woman was from Ohio and probably from not much above sea level, which is another factor that made it worse.