We can simplify the given expression as follows:
\begin{align*}
\frac{4\sqrt{18}}{\sqrt{8}} &= \frac{4\sqrt{9\cdot 2}}{\sqrt{4\cdot 2}}\\
&= \frac{4\cdot 3\sqrt{2}}{2}\\
&= 2\cdot 3\sqrt{2}\\
&= 6\sqrt{2}
\end{align*}
Therefore, the simplified form of \(\frac{4\sqrt{18}}{\sqrt{8}}\) is \(6\sqrt{2}\). So the correct option is (c) 6.