I would sit everyone down (as a team or individually depending on team dynamics) and explain to them that the client has made comments about a team member's odor. Let them know that the client's perception of us is one of the most important aspects of any engagement. Inform them that because of this, I expect everyone to ensure that they paying attention to their own hygiene and acting accordingly. If this issue continues, I would be forced to take more drastic measures.
"If person A asks you to schedule meetings, but then person B asks you to make travel arrangements, and then person C tells you to drop everything and do their tasks - what would you do and how would you prioritize?"
This was the stupidest way to ask "how do you operate under pressure, how do you prioritize" type of question. I remember when this person asked me this, all I could think of was how POORLY this question was phrased.