Hua Hin is not as busy during the nighttime as the alternatives of Phuket and Pattaya as Hua Hin is a whole lot smaller but also due to the fact that Hua Hin attracts different types of people than the before mentioned. Hua Hin is first and foremost a family destination and the activities here are created to fit these visitors.
That said, there should be enough options for most people to have a colorful night out as the city houses numerous bars and restaurants. We even have a few discotheques here.
Most of the city will close down at 2am according to Thai law but for the ones that wishes to carry on after this, small karaoke places are widely available and will be open until morning time.
Although drinking and partying is available in Hua Hin it is not a dominating factor as it is in many other tourist destinations. This is one of the reasons why we love Hua Hin.