is there any bus from xian to yulin at early morning?

There are no buses at 01:00 or 02:00 to reach Yulin. The earliest bus for Yulin directly is at 07:55 from the North Bus Station. The fare is 170RMB.
Generally speaking, you can take the local subway line 2 to reach Daminggong West and then take a taxi to reach the north bus station. If you want to know more detail routes, would you mind tell me your exact position?