Without ever meeting her in person, my guess is she is just lonely and maybe sliding into some form of dementia. Her actions, while not mainstream to you, appear to be pointing in that direction.
Hell, I'm 81, a lonely old widower, and not quite yet into following people around. But let me tell you, I have run into a few people like her, both female and male. And even some folks doing stranger stuff.
I have a 70 year old widow across the street who has around 8 cameras mounted around her place thinking the "Criminals" will be breaking in soon. And she has TWO security systems (both monitored). The police have been called for break-ins so many times, they know her by her first name (all false alarms). She still volunteers at the homeless shelter three times a week, and acts normal most times. She can "see" my house and periodically sends me a text that I have a package at my door. I just blow this stuff off.