Its In The Blood (Book 7). It's In The Blood, #7

BOOK7   The Thirst Within: EndgameThe Stunning Conclusion to the Seven-Book SagaOne final battle. One nightmare to end. One child to save them all. The nightmare realm is crumbling. After centuries of haunting the DeClue bloodline, the ancient evil of Miguel Sanchez is weaker than ever before. But a wounded monster is at its most dangerous- and Miguel will not vanish into oblivion without one final, bloody stand.
When a brutal attack leaves Angel clinging to life, the unthinkable happens. His five-year-old son, Mason, crosses into the nightmare realm alone to save his father. What emerges from the shadows is no longer a small child, but a seven-foot-tall werewolf with burning red eyes and a singular, terrifying purpose. Mason has finally awakened his true hybrid nature, and he will not rest until his family is safe.
As the DeClues gather for the ultimate confrontation, every choice they've made across seven books leads to this moment. The threats of the past have been silenced, the transformations are complete, and the ghosts are watching from the ruins of Miguel's crumbling dungeon. In this final reckoning, there is only room for one winner. Endgame is the heart-pounding conclusion to the "It's In The Blood" saga-a story of sacrifice, forgiveness, and the unbreakable bonds of a family that refused to be broken.