Here is the passage again:
O'Neil quietly closed the front door and tiptoed through the living room.
Hoping not to wake his sleeping mother, who would begin a loud and long
lecture on missing curfew.
You chose to use Punctuation Rule 3 to fix the problem:
Main clause + , + participle phrase.
The correction looks like this:
O'Neil quietly closed the front door and tiptoed through the living
room, hoping not to wake his sleeping mother,
who would begin a loud and long lecture on missing curfew.
Well done! You deserve that chocolate bar!