Question

What connotation does James achieve by adding the phrase in the annals of parental vigilance?

Answer 1

emphasizing the strangeness of Mrs. Millers behavior

Answer 2

The correct answer is the first one.

He describes Mrs. Miller's behavior as "unprecedented." By this, he is saying that, of all the parents he has ever known, her behavior is unusual, singular, or unique.

Quite simply, it is strange that she would allow her daughter to run around town with a strange man. Mrs. Miller's behavior is more than silly -- it is downright unheard of.