mrs. higgins' drawing room is A.)cluttered with nicknacks B.) similar to her son's C.) elegant and tasteful

I would go with C, everything is expensive and elegant.

I AM 100% SURE OF THIS ANSWER.

THE ANSWER IS ELEGANT AND TASTEFUL (C).

In the section from the book itself, that describes the room, it specifically points out that the room is NOT similar to her sons (which is option B), and NOT cluttered with nicknacks (option A)

Quote from the book:

"Mrs. Higgins was brought up on Morris and Burne Jones; and her room, which is very UNLIKE her son's room in Wimpole Street, is NOT crowded with furniture and little tables and nicknacks."

It goes on to talk about how beautiful, artistic, pretty, well designed, and organized, etc etc it is- which essentially is the same thing as elegant and tasteful, option C.

C is correct.