If she has made a prior public statement that she believes the wife should submit to her husband than the question would be valid as it would lead people to believe that her husband's wishes would be coming through the presidency or that she believed in traditional female roles and how would that play into her taking a very non-traditional office as a woman (at least that's how I would read into it).

If she has not made such a statement on public record (I am not sure) than the question was inappropriate and rude. Which may be the only time I defend the woman. She horrifies me.