I don't think anything can truly make up for a person being murdered or brutalized. However, the death penalty brings some comfort in knowing that the perpetrator can never harm anyone else again. The death penalty is less about punishment and justice than it is about making sure the criminal can't commit the act again.
Most people feel vindicated and sometimes joyous if the murderer of one of their family members is given the death penalty, but that in no way could ever make up for the loss of their loved one. Nothing would. There's a gaping wound that time will never mend. The death penalty may bring some satisfaction, but it in no way makes up for the crime.
The existence of the death penalty does not bring peace to the families of loved ones. For some, it may give some sense of justice, but it does not make things even or soothe the pain of losing a loved one. Many families feel that it is just another senseless death.
The families of victims may feel that they get some revenge or it may even be a way for them to vent their anger, but the death penalty cannot reverse a crime. It does not bring people back or undo the things that have been done. As families work through their grief, they must come to realize this in order to be able to release their anger.