# her masters

"the owners of the slave girl"

# their hope of profit was now gone

"their opportunity to make money was now gone" or "they could no longer expect to make money"

# their hope of profit was now gone

"she could no longer earn money for them by telling fortunes" 

# into the marketplace

"into the public square." This is a public place of business, where buying and selling of goods, cattle, or services takes place.

# before the authorities

"into the presence of the authorities" or "so that the authorities could judge them"