Like Mount Dana, the easiest summit route is one of use and unsigned, however, unlike the former peak, Mount Hoffmann has an antenna on top. The South Slope Route (mostly class 1, class 2 at the top) begins at the May Lake Trailhead at 8,346 feet and follows the standard trail to May Lake. Upon reaching May Lake, head west following the use trail that skirts the south side of the lake. Soon after the route will turn north as you begin your ascent to the summit plateau. From here you will see peaks to the west and east with the true summit being towards the west. Looking west, you'll see Hoffman's Thumb to the left. There is a short class 2 scramble to the top from where you will enjoy great views of the Yosemite High Country looking north and Clouds Rest and Half Dome looking south.
During the winter months, the summit is also a popular skiing and snowshoeing objective. Intermediate to advanced skiers can climb and ski right from the summit of Mount Hoffmann. This shortest way to reach the summit entails adding a 10 mile approach to reach the May Lake Trailhead using the Snow Creek Trail from Yosemite Valley (starting at about 4,000 feet). This trip is typically done over 2 days each way.
YOSEMITE VALLEY (aka WINTER) APPROACH: During the winter months, Tioga Road is closed and skiing (or snowshoeing) in on this road is a long trip. Many skiers use the Snow Creek Trail starting in Yosemite Valley which is plowed year round. Hiking or skinning up this trail up 8 miles will take you to Tioga Road, from where you will reach the May Lake Trailhead in another 2 miles. When you reach Tioga Road, just head straight across on to the connecting trail which parallels the dirt road described above (or go west for 0.5 miles on Tioga Road to reach the May Lake dirt road).
OVERNIGHT TRIP PERMIT: Generally there's no reason to make this an overnighter (outside of winter that is) due to the short distance, however, if you are planning an overnight trip, you will need a Wilderness Permit since YNP has a trailhead-based quota system in place. At least 40% of the permits are available on a day-of or day-before basis. See the YNP Wilderness Permits Page for more information on how to reserve these permits by the Internet, phone (209-372-0740), or mail. While the permit itself is free, if you wish to make an advance reservation, there is a non-refundable $5 per person processing fee. If you want something more plush you can stay at the May Lake High Sierra Camp which operates on a lottery basis. Applications are available between October 15 and November 30 annually. More information at the above link and the High Sierra Desk at (559) 253-5674.