Congratulations to your daughter on her graduation from NAPS! For a memorable last family trip before she begins her journey at the Naval Academy, a combined trip to the California Redwoods and Yellowstone National Park is an ambitious but rewarding choice.
The distance between the Redwood National Forest (Northern California) and Yellowstone (Wyoming/Montana) is roughly 1,000 miles (a 16–18 hour drive) across mountainous and desert terrain.
To see the tallest trees on earth, you should target Redwood National and State Parks in Northern California (near the Oregon border).
Early May is "shoulder season" in Yellowstone. This is a magical time for wildlife (baby bison and grizzly cubs!), but you must navigate road openings.