Express $\delta\in D^{'}(\mathbb R^2)$ in the form $$\delta(\phi)=\sum_{\beta}(-1)^{|\beta|}\int_{\mathbb R^2}f_\beta(x) \, (D^{\beta}\phi)(x)\ dx\ \ \ \ \ \ \ \forall \phi\in D(\mathbb R^2)$$ where $f_\beta$ is continuous function in $\mathbb R^2$.
by the result stated in rudin: since $\delta$ is a distribution of order $0$ hence $|\beta|\le2.$
I am not getting any idea how to do it. Any type of help will be appreciated. Thanks in advance.