If you have reservations about working with them, then maybe you should reconsider the opportunity. Your interviewer will place you directly into a typical scenario to gauge your insight into the field. Because each case is unique and demands flexibility and quick thinking, she wants to know how well you improvise. When you answer this question, focus on solutions. Tell your interviewer that you would talk extensively with everyone involved, from your client to her family members, to learn as much as possible about the situation and everyone's needs before making a recommendation.
Employers look for problem-solvers who get things done.
Here's your chance to sell yourself. Stress your capability of staying focused even in crisis situations. Talk about your ability to work independently while still being a team player. Point out that your genuine desire to help make life better for others is your guiding force, even in chaotic situations. Don't forget to talk about your strong organizational skills, your flexibility, and your ability to multi-task, adding how you would go about applying these traits to this particular work environment.