Xizhazi Village

I want to hike Arrow Nock on October 08. I would like to go to Xizhazi Village Oct. 07 and spend the night at Zhao's Hostel (also hire a guide). Since Oct. 07 is a Sunday, I would like to know if bus 916 runs on Sundays too (and what time it departs from Dongzhimen)?
If the minibus doesn't run from Nanda Street in Huairou can I get a taxi there that takes me to Xizhazi Village?