This View shows the last time someone in a Group was marked Attended or Confirmed.
Create your view including desired filters and add the following to the "Field List" in the SQL view:
,(SELECT MAX(E.Event_Start_Date) FROM Event_Participants EP INNER JOIN Events E ON E.Event_ID = EP.Event_ID INNER JOIN Group_Participants GP ON EP.Group_Participant_ID = GP.Group_Participant_ID WHERE GP.Group_ID = Groups.Group_ID AND EP.Participation_Status_ID IN (3,4)) AS Last_Attended