help explan

Emma, an elderly woman who resides alone, is home in the middle of the afternoon on a weekday, when she hears breaking glass. She goes to investigate and finds a neighbor boy, Bart, 15 years old, breaking out her kitchen window and trying to climb into her house. Emma yells for the boy to stop, and that he is not welcome to come in. However, Bart keeps coming through the window. As a result, Emma grabs her .38 caliber handgun and again tells Bart to stop. She also announces she has a gun and will shoot if Bart does not stop. After warning Bart on at least two occasions to stop, and seeing that Bart is still coming into her house, Emma fires her handgun once, hitting Bart in the head killing him.

Police arrive. They find Bart unarmed. Emma tells police that she know Bart from the neighborhood. She knows he is a trouble maker and has been in trouble with the police before, but she doesn't know for what type of crime. Police later determine that Bart has a juvenile record for assault, home invasions and controlled substance offenses. He was supposed to be in school at the time of the incident but was truant that day.

How does the law on the use of deadly force in self-defense apply to this scenario? Did Emma have a duty to retreat, or to do something else? Why or why not? How does the Rebuttable Presumption come into play, if at all? Will this defense be successful for Emma? Why or why not?