Mudd's Women?
1) Mudd uses drugs on the women to make them more appealing. Are the drugs illegal? Is wiving settlers illegal? Unsure. The women (appear) to come willingly. But "selling" a false product to the miners is surely a crime (as is surely the act of selling the women, whose details are never fully made clear.)
The motive?
Unsure. What could Mudd have gained? Dilithium crystals? Indeed, what was he expecting from other potential 'buyers'? Money? Credits? This was never made clear. Indeed, in the end it is Kirk and the ship that get the other end of the transaction - the crystals.
(The falsely obtaining the space craft and impersonation are crimes, but I think the motive is clear for those.)
2) We never know Mudd's exact charges, trial or even punishment. I don't think this is fully established in I, Mudd either.
3) If Mudd himself was forced into a corner before admission, who was the 'whistleblower'? It surely can't be Eve (or the other women), as she believes the fakes to be the genuine article in the penultimate scene. My guess? McCoy eventually sussed it out.