Which of the following is the correct IUPAC name of the given coordination compound?
$$\mathrm{(NH_4)_2[FeF_5(H_2O)]}$$

Nomenclature of coordinate compounds:
1.Order: Name the cation first, then the anion.
2.Ligands: List ligands alphabetically before the metal.
3.Prefixes: Use di-, tri-, tetra-, penta- for ligand quantities.
4.Anionic Complex: Add -ate to the metal name if the complex is negative.
5.Oxidation State: Write the metal's charge in Roman numerals at the end.

- Cation: Ammonium $$\mathrm{NH_4^+}$$ is named first as a separate word.

- Ligands (in alphabetical order):
- aquao or aqua $$\mathrm{H_2O}$$
- pentafluoro or pentafluorido $$5\times\mathrm{F^-}$$

- Central Metal: Because the complex ion $$\mathrm{[FeF_5(H_2O)]^{2-}}$$ carries a negative charge, the suffix -ate is appended to the Latin stem of the metal (ferrum), making it ferrate.

- Oxidation State: Calculated as +3 and written in Roman numerals:

$$\text{Oxidation State}=x+5(-1)+1(0)=-2\implies x=+3$$

Correct option: (C)