Ms Sue I am really studying hard I have one more will you check for me?

Question

Lew wasn't sure he had locked the front door so after him and Marian left for their vacation at nine o'clock they came back at 9:30.

Do I need any commas?

Answer 1

You need a comma after door and after 9:00.

Also -- him is the wrong pronoun. You need the subject pronoun, "so after he and Marian . . ."

A third correction -- be consistent -- "at 9:00, they came back at 9:30."