You answered D...

Invite both Jo and Hugh into a nearby meeting room and say: Look you two, this isn’t on. Jo, if you have a problem with Hugh’s performance give him the feedback in private. Hugh, something obviously isn’t right here – you really need to take what Jo is saying seriously.

This answer bothers us for a number of reasons. Firstly, you are now doing to Jo what you are criticising her for doing! It also makes it worse that the person you are criticising her in front of is her report. Thirdly, this approach delivers another slap to Hugh at a point when the facts of the situation that sparked this particular situation are not known to you.

Our suggestion is C

Nothing at the time but later that day find Jo and say: Jo, I know you’ve had enough of Hugh. However, I was alarmed to see you having it out with him in front of the whole room because being criticised in public probably made things much worse for Hugh - it might also make people worry about whether you would do the same to them if they crossed you. I am keen for you to apologise to Hugh, in some way.