A family feud that had its inception two years ago ended yesterday, when Levin* K. Hopkins, 75-year-old farmer, of Glen Mills, took an ax and killed his son-in-law, Samuel Stoy, 41 years old, who was asleep on a couch in the small farm house occupied by both the Hopkins and Stoy families. The murderer then ran from the scene of his crime and, using an improvised noose, ended his life by hanging from a tree near his home.