“three skeleton key” got its name as the narrator tells us from three escaped convicts.
a. after got and us
b. after name and us
c. after as
d. after three

In the above sentence, the comma should be place B. AFTER NAME AND US.

From: "Three Skeleton Key"  got its name as the narrator tells us from three escaped convicts.

To: "The Skeleton Key" got its name, as the narrator tells us, from three escaped convicts.

The pair of comma is used in the middle of the sentence to set off clauses, phrases, and words that are not essential to the meaning of the sentence.

The phrase "as the narrator tells us" is not essential to the meaning of the sentence because even with the absence of the phrase, the thought of the sentence remains the same.

"Three Skeleton Key" got its name from three escaped convicts.