The answer is C: Life is fleeting and constantly changing.
It is the same! - For, be it joy or sorrow (regardless the condition)
The path of its departure still is free: (it shows how life is fleeting)
Man's yesterday may ne'er be like his morrow; (there are so much change in one's life.)
Nought may endure but Mutability. (It seems like a paradox, but only one thing will remain: change)