Step 1: Break the name into parts:
Ligands: ethylenediamine (en), neutral, number 2 (bis). Thiocyanato ($\text{SCN}^-$), number 2 (di). Metal: Pt in +4 state.
Step 2: Add up the charges:
$+4$ from platinum, 0 from two en, and $-2$ from two thiocyanates gives $+2$.
Step 3: Write it:
Everything goes inside one square bracket with the charge outside: $[\text{Pt(en)}_2(\text{SCN})_2]^{2+}$. Only option (C) has two en, two SCN and a 2+ charge.
Final Answer:
Option (C) gives the correct formula.
\[ \boxed{[\text{Pt(en)}_2(\text{SCN})_2]^{2+}} \]