I would have sweetly told her if she's offended by the way I speak, that she's free to leave my house.
Perhaps I can let it go if she politely explain her views on this subject (without interrupting!) But ordered not to use a common word again? Uh. No.
Diana sounds like an unpleasant person to be around if comments like "kill 2 birds with 1 stone" offend her. As PP have said, perhaps she'll tone her comments down once this isn't such a new crusade for her. But if I was in my own home and was telling a story like, "So, I told him that since he was deaf to all my entreaties..." and Diana interrupted me and chastised me for using "deaf," she'd probably be treated to me saying something like, "Are you serious?" and perhaps a short lecture from me about considering the context and situation.