Let's see, if zombies, such as the standardized living dead soulless braineaters, were to be a real threat on planet Earth, then I would take my fiancee, and anyone else who wanted to live, into my interstellar battle cruiser. Leave Earth, entering into polar orbit, and systematically bombard ever square kilometer of the planet with artificial meteorites and nuclear fire. Then have the starship accelerate up to 99.999999999999999% the speed of light for a few hours of space flight around the galaxy, then return to Earth after a few centuries have past on Earth and the radiation has cleared.