From Gold Basin Rd, hike up the ridge and over to the Ridge that connects to Mt Mellenthin. You will then climb down and the back up. When you reach the top Mt Mellenthin is one hill over from the one you climbed.
WARNING! Hiking and outdoor related sports can be dangerous. Be responsible and prepare for the trip. Study the area you are entering and plan accordingly. Dress for the current and unexpected weather changes. Take plenty of water. Never go alone. Make an itinerary with your plan(s), route(s), destination(s) and expected return time. Give your itinerary to trusted family and/or friends.
To hike From Moab, go south on 191 and take the Manti-La Sal Loop road east and up into the mountains, turn right at Geyser Pass Road, and then turn right to the road into Gold Basin. There is parking along the road and at the end is a trailhead, but you want to backtrack a bit from the trailhead to ascend the ridge.