Answer
The light is 4 times brighter.
Work Step by Step
Let the initial distance from the lamp be $2d$.
$f(2d)=k(2d)^{-2}=\frac{k}{4d^{2}}$
Final distance = d.
$f(d)=kd^{-2}=4\times\frac{k}{4d^{2}}$
$\therefore$ The light is 4 times brighter.