the last one mostly depends on how seriously you take 'c'. To me it's an absolute, not to be circumstanced. Which makes my first hypothesis more plausible. If you prefer captain Kirk and faster than light it becomes different.
there exist alternative versions I've been pondering. As the one in where, even if they can communicate, might prefer not to do so. Considering our behaviors. Well knowing that this planet will try again.
Myself I define it this way. In a infinite universe there must be species that made it through, becoming a lesser infinity. But one where those that didn't are a majority. Which will mean vast distances between most of those, either able to change, or just not doing our mistakes.
So it's not a dead universe. It has life, but we belong to a place in this universe where that lesser infinity of intelligent life won't be able to communicate its existence, under that very short period we gained the tech to hear them. As we're currently walking over the edge, in several ways, we will never know if I was correct there too.
" It may be solemn, but becoming concerned for humanity's extinction is nothing other than realising one's obligation to strive for unceasing self-betterment. Indeed, ever since the Enlightenment, we have progressively realised that we must think and act ever better because, should we not, we may never think or act again. And that seems - to me at least - like a very rational end of the world."