OTOH, how could it happen accidentally if it would be too much to endure in a suicide attempt? I guess you could say she might have passed out under relatively minor heat stress, making it an accident.
I think she must have been really passed out, from either natural or induced causes. She must have just been out cold. I don’t even know if you could be that drunk, that you wouldn’t wake up from discomfort, but I guess they are saying the mom too died from hyperthermia, so I don’t know.