I've never done a jam on itch.io, so I don't know how the topics are given.

Is A) "isolation" the topic, or is B) "Isolation" the name of this jam, and the topic will be given once the jam starts?

The theme/topic of this game jam is Isolation. However this game jam also has a limitation, a restriction or set of restrictions that your game must adhere by. The limitation will be announced on the Discord server as soon as the jam starts and the limitation section of the jam page will be updated..