Is there an option to start a conference in Communities?

No. The Communities are designed for a broadcast style of communication where you usually ask whole community to discuss different topics and give ideas.

To have the real-time audio and video conferences in these conversations, we feel we would need to support broadcast style conferencing, with all conference moderation features, such as Mute all, Lock, Raise hand, etc. We are looking at introducing these features, but until then, we do not want to add real-time in Community type of conversations and end up with a bad user experience.