Which mother guarded the bodies of her hanged sons from birds and beasts?

Answer: Rizpah

Saul's concubine Rizpah spread sackcloth on a rock and kept watch from the harvest until the rain came. David then buried the bones.

“But the king took Armoni and Mephibosheth, the two sons whom Rizpah daughter of Aiah had borne to Saul, as well as the five sons whom Merab daughter of Saul had borne to Adriel son of Barzillai the Meholathite.”— 2 Samuel 21:8 (BSB)