Regarding Wilkinson's catalyst, the correct statement is

Coordination number is four.

Oxidation number of Rhodium is ‘+1’.

Ligands involved are three triphenyl phosphine and one chloride ion.

$\left[\mathrm{RhCl}{\left({\mathrm{Ph}}_3\mathrm{P}\right)}_3\right]$ is Wilkinson's catalyst used in hydrogenation of alkenes;