Despite the owlbear almost taking out two party members, as well as King Grol and his pet wolf attacking from the rear, the party prevailed.
They stabilised Grol, hoping to question him. Actually, they stabilised him twice, after the barbarian attacked the stable Grol, knocking him back into life-threatening danger.
While they waited for people to recover, they explored the rest of the crumbling castle.
This exploration was chaotic.
One person fell from a 40 ft high ledge and fell unconscious, dying, far from the rest of the party. Thankfully the party got there in time. They bravely rescued a treasure chest and took it back to Grol's room, since that was more important than stabilising the dying party member.
Another person tripped a rockfall trap and fell unconscious, dying, far from the rest of the party. It took the combined effort of all their healers to stabilise him while everyone else moved a thousand pounds of rocks off his broken and injured body.
Buddy rule, guys!
The party cleansed a shrine that had been taken over by a goblin priest of Maglubiyet. It seems like the gods approve. Well, not Maglubiyet, obviously.
Questioning Grol didn't tell them much they didn't already know. Grol had seen his dreams of a Goblin tribe all his own completely shattered. He saw his troops killed. He saw his secret weapon, the owlbear, dead in a pool of blood. He saw his best friend in the world killed before his eyes. When the party killed him, it was a merciful end.
That said, he was a murderous bandit allied with a Drow torturer, so don't have too much sympathy for him.
And so comes to a close the story of the Cragmaw Goblins and of Grol, a hobgoblin who would have been a King. I coudda bin a contender.
The party spent the night in the castle. They then headed for Phandelin. Two days later, late in the afternoon of the 9th day of Tarsakh, the party reaches the outskirts of town.
491 XP each for King Grol, his wolf, and owlbear, total 1656 XP.
This includes a 100 XP each award for cleansing the temple and a 200 XP each award for the end of the Cragmaw Tribe story.