There are hostels and restaurants in all the main access towns of the Cordillera Huayhuash . But if you choose to trek with an organized agency, you will probably never visit them. In Chiquián, try the Hostal Nogales (Comercio 1301, three blocks from main square, tel. 043/74-7121, hotel_nogales_chiquian [at] yahoo [dot] com.p, US$6 s, US$12 d, cheaper rooms have shared bath).
In Cajatambo, try Tambomachay  (Bolognesi 140, Lima tel. 01/244-2046, US$10 s, US$15 d) or the upscale International Inn (Benavides, block 4, Lima tel. 01/244-2071, international.inn [at] hostal [dot] net, US$40 s, US$50 d, prices negotiable).
There are a few basic hostels in Huallanca, from where public transport leaves to Matacancha and Ishpac (90 minutes).