Cannot place center while using multirow

I suppose you want the multirows contents vertically centred, which can be done by trial and error using the vertical move optional argument.

I added some padding to the cells with the cellspace package, and a more sensible spacing between caption and table with the caption package.

\documentclass{article}
\usepackage{amsmath}
\usepackage{multirow, caption}
\usepackage{cellspace}
\setlength{\cellspacetoplimit}{4pt}
\setlength{\cellspacebottomlimit}{4pt}
\usepackage[table]{xcolor}

\begin{document}

\begin{table}[h]
    \centering
    \caption{Tabel Turunan Numerik Beda Hingga}
    \label{tabelbedahingga}
        \begin{tabular}{|c|c|Sc|Sc|}
            \hline
            \rowcolor{green!10}
            \multicolumn{2}{|c|}{Beda Hingga}&Rumus&Orde Kesalahan\\
            \hline
            \multirow{2}{*}[-1.6ex]{Beda Maju}&Turunan Pertama&$y'_i =\dfrac{y_{i+1}-y_{i}}{h}$&$O(h)$\\
            \cline{2-3}
            &Turunan Kedua&$y''_i =\dfrac{y_{i+2}-2y_{i+1}+y_i}{h^2}$&$O(h)$\\
            \hline
            \multirow{2}{*}[-1.6ex]{Beda Mundur}&Turunan Pertama&$y'_i=\dfrac{y_{i}-y_{i-1}}{h}$&$O(h)$\\
            \cline{2-3}
            &Turunan Kedua&$y''_i =\dfrac{y_{i}-2y_{i-1}+y_{i-2}}{h^2}$&$O(h)$\\
            \hline
            \multirow{3}{*}[-3.5ex]{Beda Pusat} &Turunan Pertama&$y'_i=\dfrac{y_{i+1}-y_{i-1}}{2h}$&$O(h^2)$\\
            \cline{2-3}
            &\multirow{2}{*}[-1.7ex]{Turunan Kedua}&$y''_i =\dfrac{y_{i+2}-2y_{i}+y_{i-2}}{4h^2}$&$O(h^2)$\\
            \cline{3-3}
            &&$y''_i =\dfrac{y_{i+1}-2y_{i}+y_{i-1}}{h^2}$&$O(h^2)$\\
            \hline
        \end{tabular}
\end{table}

    \end{document} 

Vertical centering of cell contents is not a trivial issue.

The previous answer just solves the problem by using manual adjustment. Another approach could be lying about the row number in the \multirow statements. It is shown below.

This also solves the cosmetic matter. However, in my opinion they are not satisfactory solutions, and I would love a general method to do this.

\documentclass{article}

\usepackage{amsmath}
\usepackage{multirow,cellspace,caption}
\usepackage[table]{xcolor}
\usepackage{graphicx}

\setlength{\cellspacetoplimit}{4pt}
\setlength{\cellspacebottomlimit}{4pt}

\begin{document}
\begin{table}[h]
    \centering
    \caption{Tabel Turunan Numerik Beda Hingga}
    \label{tabelbedahingga}
        \begin{tabular}{|c|c|Sc|c|}
        \hline
        \rowcolor{green!10}
        \multicolumn{2}{|c|}{Beda Hingga} & Rumus & Orde Kesalahan\\
        \hline
        \multirow{3}{*}{Beda Maju}
            & Turunan Pertama & $y'_i =\dfrac{y_{i+1}-y_{i}}{h}$&$O(h)$\\
            \cline{2-3}
            & Turunan Kedua & $y''_i =\dfrac{y_{i+2}-2y_{i+1}+y_i}{h^2} $ & $O(h)$ \\
        \hline
        \multirow{3}{*}{Beda Mundur}
            & Turunan Pertama & $y'_i=\dfrac{y_{i}-y_{i-1}}{h}$&$O(h)$\\
            \cline{2-3}
            & Turunan Kedua & $y''_i =\dfrac{y_{i}-2y_{i-1}+y_{i-2}}{h^2}$&$O(h)$\\
        \hline
        \multirow{5}{*}{Beda Pusat}
            & Turunan Pertama & $y'_i=\dfrac{y_{i+1}-y_{i-1}}{2h}$&$O(h^2)$\\
            \cline{2-3}
            & \multirow{3}{*}{Turunan Kedua} 
                & $y''_i =\dfrac{y_{i+2}-2y_{i}+y_{i-2}}{4h^2}$&$O(h^2)$\\
                \cline{3-3}
            &   & $y''_i =\dfrac{y_{i+1}-2y_{i}+y_{i-1}}{h^2}$&$O(h^2)$\\
        \hline
        \end{tabular}
\end{table}
\end{document}