According to our current understanding of physics, it is not possible for an object with mass to move at or exceed the speed of light in a vacuum, as described by Einstein's theory of relativity. The speed of light in a vacuum, denoted by "c," is considered to be the ultimate speed limit of the universe.
In the scenario you described, if you were hypothetically moving at the speed of light and you threw a stone in front of you, the stone would not exceed the speed of light. This is because the stone would inherit your velocity relative to an observer at rest, but both you and the stone would still have velocities below the speed of light relative to that observer.
According to special relativity, as an object with mass approaches the speed of light, its energy and momentum increase significantly. However, the object's mass also increases, causing its kinetic energy to approach infinity as it approaches the speed of light. This implies that it would require an infinite amount of energy to accelerate a massive object to the speed of light.
Therefore, regardless of the circumstances, it is not possible for an object with mass to travel at or surpass the speed of light. The speed of light acts as an absolute cosmic speed limit within our current understanding of physics.