Answer:
My sister, who is a waitress at Billy's Big Burger Shack, is sixteen years old.
Step-by-step explanation:
In the first sentence, "president of the National Honor Society" is a non-essential appositive, therefore it should be set off with commas. In the second sentence, "that my father grew up in" is an essential relative clause because it is necessary to define an otherwise vague subject ("The old house"), and essential clauses are not set off from the main sentence with commas; the essential relative clause in the third sentence is thus properly punctuated. In the last sentence, there should not be a comma separating the subject from the predicate for no reason.