There’s one hotel, Arimune, in Bakio.
We rented an apartment through Airbnb in the building where we used to have a place (the apartment building is named “Portugane.”)
This Airbnb rental in Portugane is also now available — let the owner know I sent you:
https://www.airbnb.com/rooms/8306980
Otherwise, you could stay in Bilbao which has a good range of hotels, especially around the Frank Geary-designed Guggenheim Museum. We have a travel agent in Bilbao who can help, if you’d like, with hotels and other plans.