Answer: C. He is the last of the Old Ones and it is his destiny.
Old Ones was the name referring to ancient warriors serving The Light. Four of them took Will to travel through time and space to reach the place so-called the Great Hall which at the present time, the church that Will Staton's family attend to. He was informed that he is the last Old Ones member as being the seventh son who gained his powers on his fourteenth birthday.