Freddy didn't actually die in "Freddy's Dead: the final Nightmare"!
He didnt die for good in Freddy's Dead because in Freddys dead every child in Springwood had been killed and 1428 Elm was all boarded up and stuff and then of course Freddy "died" at the end, so then obiously a whole lot of new teens moved to Springwood including Lori who moved into the "newly remodeled" 1428 Elm, but then Freddy came back and killed Lori's Mum, so really Freddy wasn't gone for good in "Freddy's dead: the final Nightmare" the title lied.