B: すみません この本はお貸しできません。
I got a little confused when it comes to these word like お借り、お貸し。
Japanese Language Stack Exchange is a question and answer site for students, teachers, and linguists wanting to discuss the finer points of the Japanese language. It only takes a minute to sign up.Sign up to join this community
お貸しする is a "humble" way of saying 貸す and similar for お借りする, a "humble" form of 借りる.
There is lots of information on the web about these, for example here on this site: