I think Vaughn is a Beautiful Strong name with Margaret it adds softness with a vintage feel. Any of those choices are beautiful except I'm not very fond of the last choice. But ultimately name her what feels right! What makes you and your husband happy!
MaeveAmelia is stunning! Two gorgeous names. Vaughn on a girl is terrible, in my opinion. It would sound like you have two boys. I do love Margaret, but I am not crazy about it paired with Maeve. MargaretAmelia would also be lovely.