Car rental Hehua airport to Wulingyuan

Generally speaking, it costs CNY 200 to 250 for the single trip.
Upon landing, you can find several car rental companies. So it's not necessary for you to book it in advance. If you think that the cost is expensive, sharing a car with others is also a good choice.

Does the bus or train drive at that time of the day?

Train doesn't lead to the airport and no direct bus is in service during that hour. I suggest you take a taxi to ZJJ City at a cost of CNY30 and stay there overnight. In the next morning, you can easily catch a direct bus to Wulingyuan Scenic Area at local Long-distance Bus Station.

Thank you, you guys are awesome for answering so quick!