After the victory of Beowulf over Grendel, Grendel's mother took vengeance by abducting King Hrothgar's 'most beloved friend' Aeschere. This brought sorrow to King Hrothgar
Explanation
In the poem 'Beowulf', the poet talks about the courageous acts of Beowulf.
Grendel, a monster started his series of attacks in Danes after the feast held by King Hrothgar.
Beowulf from the tribe Geats who came to know about these attacks helped King Hrothgar by attacking Grendel and killing him.
King Hrothgar was glad and grateful to Beowulf.
The King threw a party commemorating Beowulf's victory.
On the same night, Grendel's mother took this vengeance.