There isn’t one. When the sun goes supernova, we’re in the way! Humanities best defence is to develop space travel and set up colonies on other planets in other solar systems. So technology is the best defence to save us, but the planet is probably toast.
Some scientists believe that our sun may not become a supernova because it doesn’t have enough mass. Instead, the s.un will shrink and become a white dwarf towards the end of its life. A white dwarf is much cooler than our sun now so temperatures on Earth may become too low to support human life.
As Katherine mentioned, there’s nothing much we can do about it except to look for new planets to colonize, assuming that humans are not extinct 5 billion years from now when the sun reaches the end of its life!