The set which does not have ambidentate ligand(s) is

An ambidentate ligand is a ligand that can coordinate to the central metal atom through two different donor atoms. Examples include NO$$_2^-$$ (through N or O), NCS$$^-$$ (through N or S), and EDTA$$^{4-}$$ (can coordinate through N or O atoms at different sites).

Let us check each set:

Option 1: C$$_2$$O$$_4^{2-}$$, ethylene diamine, H$$_2$$O

- C$$_2$$O$$_4^{2-}$$ (oxalate): bidentate ligand, coordinates through two O atoms (same type) — not ambidentate

- Ethylene diamine: bidentate ligand, coordinates through two N atoms (same type) — not ambidentate

- H$$_2$$O: monodentate ligand, coordinates through O — not ambidentate

None of these are ambidentate.

Option 2: Contains NCS$$^-$$ which is ambidentate (can bind through N or S).

Option 3: Contains NO$$_2^-$$ which is ambidentate (can bind through N or O).

Option 4: Contains both NO$$_2^-$$ and NCS$$^-$$, both ambidentate.

Therefore, the set that does NOT have any ambidentate ligand is Option 1: C$$_2$$O$$_4^{2-}$$, ethylene diamine, H$$_2$$O.