I was doing the bail bond mission with Trevor and found the second character Maude requested but on engaging his gang members i accidentally killed him, I know there is a way to replay all the main missions, strangers and freaks etc but is there a way to replay this bail bond mission?
According to the info from GTA forums and players it would seem that there is no way to replay the bail bond missions.
So if you want the achievement of returning one of them alive, you should be careful and save before the missions. You only need to return one of them alive to get the achievement/trophy. Here's a thread about the bail bond missions.