PhD Thesis based on published articles on different topics
First of all, writing a PhD dissertation in 2 months is one hell of a task. You should probably talk to your supervisor about more time.

I believe it is not uncommon, as Thomas stated in the comments, that people assemble a PhD disseration from the publications they had during their time. Many people work of different topics at the same time, but usually there is something that combines them. The title of your dissertation can be very vague and cover a wide topic. In your dissertation you can split it into different chapters of sections according to your covered topics. Of course, it is good if you find a common thread and can build upon that. Even if you don't, I still think it is okay. After all, that seems to be what your supervisor wants.

If you are really unsure, there is no way around talking to your supervisor about it. Ask for his expectations and tell him about your plans. Then, you will be able to meet somewhere in the middle.