Answer
Use the relativistic velocity formula.
Work Step by Step
$$v=\frac{v_{1}+v_{2}}{1+\frac{v_{1}v_{2}}{c^{2}}}$$
Substitute the numbers.
$$v=\frac{c+c}{1+\frac{c \times c}{c^{2}}}=c$$
Relative to the Earth, the drone still moves at c, the speed of light.