Bus missed her, so she had to walk home, parent was upset that she had to walk home in the first place and was threatening employees.
No further information do I have, but her primary statement was "I can't believe she had to walk a mile and a half home."
Well I'll take the story here.
1) The student made the mistake and was late to the bus or bus line. Teachers don't have rosters for busses. Tough bananas Mom, talk to your kid.
2) Teacher held the student late. Why did the teacher hold the student late? The teacher had better have a DAMN GOOD reason for it. Talk to the teacher in question and your child.
3) An 11 year old should be able to make it to the bus by themselves, it's the kid's responsiblity.
And other brainstorms:
1) Helicopter parent who is over protective
2) Is this a vulnerable child?
3) Has the child EVER walked home? This could be scary for a parent.
4) Did the kid need to be somewhere at a certain time? It's was probably a 30 minute walk.
5) What kind of area did the child need to walk through? Our kids have to walk past some six-offenders if they were to walk home.
6) Change in routine can be scary
7) Some districts don't have busing at that distance, or up to 2 miles away. (like I said, I'm brainstorm and just spouting out statements)
8) I used to walk across a frozen lake to school, and yes it was up hill both ways...it was a kettle lake

9) Parent who reacts before checking in with child