A small electric dipole $\overrightarrow{\mathrm{p}}={10}^{-9} \widehat{\mathrm{i}}\mathrm{N}/\mathrm{C}$ is placed at the origin. $A(1,0m)$ and $B(0,1m)$ are two points. Then $(V_A-V_B)$ is 

x-axis is the equatorial line of the dipole and potential of any point on the equatorial line is zero. 

Hence $V_B=0$ and $V_A=\frac{1}{4\pi {\in }_0}.\frac{p}{r^2}=9\times {10}^9\times \frac{{10}^{-9}}{{\left(1\right)}^2}V=9\text{\hspace{0.17em}volt}$

$\therefore V_A-V_B=9\text{\hspace{0.17em}volt}.$