In britain it has largely become a matter of taste and personal preference as to which of chairman, chairperson, or chair are used. Chairwoman would be unusual unless it were of an organisation Ò€¦ Ladies is the plural form of lady, so the apostrophe goes to the right - ladies'.

For work-place specific gender-neutral politically-correct terms refer to the answer by @third-news. Otherwise, as elliot frisch has suggested, lady is the term you want. But in my opinion, if you're Ò€¦