How can I go to Citadines Central Xi'an hotel ?My arrival flight is 02.10 am. by airport bus

You can take shuttle bus Xishaomen Line to the last stop, which is about 6km southwest to your hotel. The bus runs till the arrival of the last flight. You need to catch a taxi then. BTW, the bus takes about 70 minutes and 25 RMB, and the taxi is takes about 15 minutes and around 20 RMB.