Yes people tend to project their own thought process and behavioral patterns onto others, they assume everyone is like them.I think there are a lot of presumptions based on personal bias. We've had opinions on driving at night, hearing, taking uber to family's house, opening front doors and other patterns a person may do.
Many are basing this in their own personal bias, but everyone is so different. I would love to talk to her immediate family and get a vibe check on these possibilities, surely they would know better.
I was thinking the same thing, LE should talk to family and ask for their best guesses about how NG would act in various situations. They should also talk to NG's close older women friends. Older women can let their hair down with their peer group, relax a bit, and might confide more to them than to the kids and grandkids. For example if anything was worrying NG, or if she had noticed something odd. Sometimes older women don't want to bother or upset the kids or grandkids but will talk to their friends.