What happens soon after Beowulf engages grenades mother in battle?

After engaging Grendel's mother in battle, Beowulf successfully decapitates her with a magical sWord he finds in her lair, thus avenging the death of Hrothgar's advisor, Aeschere. Beowulf emerges victorious and returns to Heorot with Grendel's head and the hilt of the sWord as proof of his triumph.