d) Cut off its head and brought it to Hrothgar as a trophy.
Explanation:
he lair becomes brighter after Grendel's mother dies, and Beowulf is able to inspect his surroundings. He finds Grendel's body and, to take further revenge, he decapitates the corpse. ... The Geats return to Heorot Hall, taking Grendel's enormous severed head with them.
This quote means that whoever wrote this quote thinks that people who are dead (which is what he means by inhabitants of the deep) are a lot more happy than him/her.
