[guided]Fix $p\in M\setminus\mathcal S$. Because $M\setminus\mathcal S$ is open, choose $r_p>0$ so that the closed geodesic ball $\overline{B_g(p,r_p)}$ is compact and contained in $M\setminus\mathcal S$. The previous step gives a finite constant $C_p$ with
\begin{align*}
\sup_{x\in \overline{B_g(p,r_p)}\cap\Sigma_k}|A_{\Sigma_k}|(x)\le C_p
\end{align*}
for all sufficiently large $k$.
We now apply embedded local graphical compactness for minimal surfaces on $B_g(p,r_p)$. The required hypotheses are: embeddedness, the minimal surface equation, smooth bounded ambient geometry on the compact ball, uniform second-fundamental-form bounds, and local finiteness of the number of sheets. Embeddedness and minimality are hypotheses on $\Sigma_k$. Smooth bounded ambient geometry follows because $\overline{B_g(p,r_p)}$ is compact in the smooth Riemannian manifold $(M,g)$. The curvature bound is the displayed estimate.
It remains to justify local finiteness of the sheet number. The graphical-radius estimate for embedded minimal surfaces with $|A_{\Sigma_k}|\le C_p$ in a compact ambient ball gives a radius $\theta_p>0$, depending only on $(M,g)$, $r_p$, and $C_p$, on which each sheet crossing $B_g(p,r_p/2)$ is graphical. The local monotonicity or graphical-area estimate then gives a constant $c_p>0$ such that each such sheet contributes at least $c_p$ of $\mathcal H^2$-area inside $B_g(p,r_p)$. Since
\begin{align*}
\mathcal H^2(\Sigma_k\cap B_g(p,r_p))\le \mathcal H^2(\Sigma_k)\le A_0,
\end{align*}
the number of sheets crossing $B_g(p,r_p/2)$ is bounded above by $\lfloor A_0/c_p\rfloor$. This is the precise place where the global area bound is converted into local sheet-counting control.
The theorem therefore gives a subsequence, depending on $p$, for which $\Sigma_k\cap B_g(p,r_p/2)$ converges smoothly on compact subsets, with locally finite multiplicity, to a smooth embedded minimal lamination $\mathcal L_p$ of $B_g(p,r_p/2)$.[/guided]