What did the dame of fifty want to do to Hester?

The "dame of fifty" wanted Hester to be tried by the Goodwives.

“Goodwives,” said a hard-featured dame of fifty, “I'll tell ye a piece of my mind. It would be greatly for the public behoof, if we women, being of mature age and church-members in good repute, should have the handling of such malefactresses as this Hester Prynne. What think ye, gossips? If the hussy stood up for judgment before us five, that are now here in a knot together, would she come off with such a sentence as the worshipful magistrates have awarded? Marry, I trow not!”