No, I don´t think there is such option in DA2. You can give her to Qunari and they will leave with her. According to wiki, at the start of Act III, Varric mentions she might have escaped.
Yeah, didn't mean it as an option for the player, just what would logically happen if given to the Arishok.
As for the bolded part I did not actually know that. In my 8(?) playthroughs I have never done 2 things, side with Petrice or give Isabella up 
This is where the comics pick up, right? Bela is a crafty lady, not even the arishok can stop her 
Comics consider Hawke fighting the Arishok as canon though, can't happen if you give Isabella up