We will arrive xian airport at 11pm, can we take shuttle to xishaomen?

Yes, according to your arrival time, there still have airport shuttle bus that can take you to Xishaomen Airport Business Hotel and the bus actually operates till the arrival of the last flight. It takes around an hour on the way. The ticket fare is CNY 25 per person. After that, you can take a taxi to get to your hotel. The cab fare is CNY 15 to 20 in the night.

Generally speaking, it's not necessary for you to worry about the safety problem.

First of all, the city is quite safe. It is fine to take a taxi to your hotel directly. The reference fare is CNY130-150.