Yes I thought that this was a bit weird too. Also that even if this was an HR Manager (of the school board, of the teachers, whatever), making a call like this is in no HR Manager job description I've ever heard of. (And yes, I have heard of HR Managers overstepping their bounds, but never in any scenario even remotely resembling this one).
OP are you absolutely sure it was an HR Manager associated with the school or board that made this call?
(And to some of the others posting here, I don't think OP was told to stop walking her daughter to school - nobody can prohibit that, and certainly not a possibly-faux HR Manager, I think OP was told to stop walking her daughter to class - which I took to mean OP cannot go into the school with her daughter, she must leave her daughter at the school door.)

