The correct answer is the following: option B. At the end of the sentence provided in the question the narrator alludes to the possibility of requiring a wife who could match Adam social standards.
"The Million Pound Bank-Note" is a short story written by American author Mark Twain that was first published in 1893. It tells the story of an American man named Henry who is poor and now living in he city of London. Henry Adams is given an envelope with a 1.000.000 pound bank-note that in the case that he would try to exchange it in the bank, would probably send him to prison. Still Henry starts to see how by having that bank-note in his power, people are assured that he is wealthy and therefore he can live in the city as a rich man, without ever spending the 1.000.000 pound bank-note.
This is why the narrator is alluding that Adams requires a wife who could match Adam social standards. She can be cheerful in moments there was no reason to be cheerful at all, and Adams knows that his social status can suddenly drastically change, and he needs someone like her by his side.