The parents of an Army Green Beret who was killed in Afghanistan will be guests at President Obama’s final State of the Union address.Carol and Peter McKenna of Bristol are the parents of U.S. Army Special Forces 1st Sgt. P. Andrew McKenna Jr., who died during an attack in Kabul on Aug. 7. Democratic U.S. Rep. David Cicilline invited them to Tuesday’s State of the Union. Each member of Congress gets one guest ticket. A Minnesota Democrat donated his so both McKenna parents could go.