answer: Joanna's husband David picks up Bill because Joanna works late.
documents: #Person1#: Excuse me, are you Dr. Smith?
  #Person2#: Yes I am. And you. . .
  #Person1#: I'm David, Joanna's husband. She has to be at work late today. So she asked me to pick you up here.
  #Person2#: So nice to meet you, David. Call me Bill. It's very nice of you to come here.
  #Person1#: My pleasure.