From Tunica, go east on Hwy 304 to Senatobia.
Take I-55 South to the Vaiden exit, where you'll get on Hwy 35 South.
Stay on Hwy 35 South through Kosciusko (watch the signs), until you get to Carthage. There, turn left (east) on Hwy 16. Pearl River Resort is about 20 miles from there IIRC. You can't miss it.
Leaving Pearl River Resort, you'll want to head into Philadelphia, and take Hwy 19 South to Meridian.