Yes, she should have blocked the number. However, I should always lock the front door. If I don't, that doesn't mean that it's okay for you to come in.
By that logic, no one should ever call your home without permission, even a friend! Walking into someone's house is much, much different than calling someone, IMO. I would never walk into my friend's house unannounced, but I would call them at 7:30 at night without getting permission first.
As for the time, I have lots of friends for whom 7:30 pm is bathtime. If I were elbow deep in suds and answered my phone without thinking (because that's something that is easy to do when I'm distracted,) I would be super annoyed.
I posted to the OP that I completely get being annoyed, I just don't think that what happened makes the parent a stalker who violated her. Like I said, if I was dealing with 250 students and associated parents, there's bound to be one or two in the bunch that have poor social skills or lack of boundaries. What do you do if you're working with that many people with faults and foibles all day, every day? I would be surprised, honestly, that I didn't get more weirdness invading my personal life on a more consistent basis!
~J, wife to one and mama to three wild and crazy guys!~