What to wear to a formal meeting with a social worker?

Me and my daughter both have to go to a meeting with her social workers. Becky will probably just play so her outfit needs to be comfy but still not sloppy, no dresses or skirts I am unable to push her into wearing them, she is autistic so I can't push her. I was thinking just some smart pants and a t-shirt for her. What do you think? And then I have no idea what I should wear, I never normally have these meetings, usually they are very casual and they come to our home to assess how she reacts to her enviroment and surroundings and also around me. But this is all about her bio parents who were jailed for neglect and abuse, and I have no idea what to wear. Help????