During James Monroe's presidency (1817-1825), the Supreme Court expanded the power of the federal government primarily through its rulings related to economic regulation and federal authority over interstate commerce. The most notable case that exemplified this expansion was McCulloch v. Maryland (1819).
In McCulloch v. Maryland, the Supreme Court ruled that the federal government had implied powers beyond those enumerated in the Constitution, specifically allowing for the creation of a national bank. The decision affirmed that federal laws take precedence over state laws, establishing a stronger federal presence in economic matters. This case supported the idea that the federal government could regulate aspects of the economy, thus aligning with your option "It gave the federal government power to regulate the economy."
Therefore, the answer that best fits the context of the question is: It gave the federal government power to regulate the economy.