The correct possessive spelling of lady? is it Lady's, Ladys' Ladies'?
The correct possessive spelling of lady is lady's, if you are referring to one lady, or ladies' if you are referring to more than one lady owning the same object.
The correct possessive spelling of lady depends on how many ladies own the object. For lady, the possessive singular is a different word than the possessive plural when written, but it is pronounced the same.
He observed the lady's grimace as she joined the long line towards the ladies' room.
She observed the man's smile as he joined the shorter line towards the men's room.