Solution (source code)

= Solution

Yes. The local $L^1$-to-$L^\infty$ estimate for solutions of a uniformly elliptic equation with bounded Hölder coefficients gives, whenever $B_r\Subset B_R$,
$$
|u_k-v_m|_{0;B_r}
\leq C\lVert u_k-u_m\rVert_{L^1(B_R)}.
$$
Thus $(u_k)$ is locally uniformly Cauchy and converges locally uniformly to a continuous representative of the $L^1$ limit $v$. Part (b) then applies, so $v\in C^2(B)$ and $Lv=0$.