Which among the following is the most stable?

The correct option is B $T{i}^{4+}$
Electronic configuration:
$T{i}^{2+}:\left[Ar\right]3d^{2}4s^0$
$T{i}^{3+}:\left[Ar\right]3d^{1}4s^0$
$T{i}^{4+}:\left[Ar\right]3d^{0}4s^0$
Since, $T{i}^4$ attains an inert gas configuration, it is the most stable.