All my opinion, and frankly not worth much. I honestly believed an incident had happened, but given the news about NB's struggles and challenges, its not out of the question that her walks, as mentioned by other members here, could have been her place to have a drink, or similar, and something has gone wrong as a result of this, and her mental state. Addiction is an illness, and being an addict doesn't mean a person is unkind, or bad, despite addiction causing behaviour that could be seen as bad/poor/selfish/whatever. Alcohol is a complicated one, I have some first hand experience of a tee total female, who started drinking in her late 30s, and died within a decade, not what I was conditioned to believe was the typical path for this sort of thing.
One thing is for sure, its absolutely awful and God bless NB, and her family, there were clearly struggles and I doubt we know all of them, like so many others have, in this ever more complex world.