D. I suspect that the universe will not end, it will be reorganized though at some point when the "Brane" of this one contacts the "Brane" of another.

D. When I pass away.

My guess is the Big Crunch. I'll let you know in a few billion years if I'm right.

I have no better answer than Frost

Some say the world will end in fire;
Some say in ice.
From what I've tasted of desire,
I hold with those who favor fire.
But if it had to perish twice,
I think I know enough of hate
To say that for destruction
Ice is also great and would suffice.

D. The universe will end when we do. What we perceive as the universe is just a spacial domain. Once we leave that domain it ceases to exist from our perspective and we cease to exist in it from the universes perspective.

Overall the energy in the universe may possibly be being lost using the principles of speed of light = wavelength multiplied by velocity (c = w x f). As the universe expands and the wavelength of photons becomes larger frequency decreases. And since E=hf, energy is lost somehow. Now I have another theory on where the energy goes but someone told me that it may convert to mass but that doesn't seem to make sense as a photon is described as a particle with a very small relative mass or mass less.

D. The Universe will not end. It had no beginning and will have no end. If the 1st law of thermodynamics is right, energy is eternal. The definition of Universe is everything. If the universe were to end, everything would have to cease to exist. There may be rips, chills and crunches, but these are not the end.

When that Trafalmadorian hits the wrong switch, as referenced in Slaughterhouse Five by Vonnegut, it has been and it will always be that way...