Answer:
It's correct!
Explanation:
According to Grammarly, the sentence is correct! Have a look:
What do you need help on?
Because she promised them to Maggie when she marries John Thomas
"I promised to give them quilts to Maggie, for when she marries John Thomas"
The bold is from the story
An omniscient narrator knows everything necessary to relay the story to the reader. The correct answer is A.