[4Zoltan]

Any chance she never talked about it with him or that she herself was unaware that she had a problem?

I know that sounds crazy but stranger things have happened in families.

She was a tad overweight and 65 years old.

[trisham]

Both scenarios are possible, but without the crash, would she have died on that day?

Imho, this is much like the bank robbery gone bad, where the person who drove the getaway car is considered to be as culpable as the person who shot the bank guard.