If the world was ending...

Running on empty (Jackson Brown)

I'll go with "my girl", I have heard it so many times, that one more would probably kill me..

I doubt music would be the first thing on my mind in that situation, but I think Say Goodbye by The Year of the Rabbit would be end of the world appropriate. And comes in just under 5 minutes to take full advantage of the arbitrary time limit.

Lukas Graham - Funeral

Hurt - Nine inch Nails, the Johnny Cash version