A Massive star either ends up as neutron star or a black hole.
When fuel is used up, the star expands and becomes a Red super giant and goes supernova. Most of the material is thrown out which forms planetary nebula. The core collapses in seconds to form Neutron star or black hole. A star having mass more than 3 solar masses usually collapses to form black hole.
Thus, a 50 solar mass star would likely become a black hole after it goes supernova.
