I met with a friend of Molly's
I met with a friend of a friend
I met with a friend's friend

Is the first right and the other two wrong?
I understand that one might use such phrasing for aesthetic value; so does that mean that it's use is 'wrong', or rather, should be avoided, if purely utilitarian? E.g. 'The Tempest of Shakespeare’s'.

Spend your weekend well!