How might Mr. Bennet's earlier actions have prevented this scandal? Is Mr. Bennet responsible for his youngest daughter's behavior?

Mr. Bennet has always been compacent when it came to the well being of his daughters. Mr. Bennet's main interest was that his daughters married into money. Wickham was obviously a pompous jerk but he was also a wealthy well connected jerk. Mr. Bennet encouraged Lydia on this basis. If he loved his daughter, he might have encouraged her to seek a better man.