Jehoshaphat is the grandson of Maachah. She is the wife of King Abijam.

Source:

1^st Kings 15:10, 1^st Kings 20:24

Who is the Grandmother of Rehoboam? This King caused Israel to split into two kingdoms.

Rehoboam is the grandson of Bathsheba the mother of Solomon with King David.

Source:

2^nd Samuel 11:24, 1^st Kings 11:43

Through tragedy this woman became the grandmother of Obed. Who is she?

This woman is Naomi the mother in law of Ruth.

Source:

Ruth 4:13-17

Joseph, the one in the book of Genesis. Who is his grandmother?

Joseph is the Grandson of Isaac through his son Jacob and Rachel. Therefore the Grandmother is Rebekah.

Source: Genesis 25:19-26, Genesis 30:22-24

Who is the Grandmother of the twins Jacob and Esau?

Issac is the son of Abraham and Sarah. Therefore Sarah(Sari) is the grandmother.

Source:

Genesis 21:3, Genesis 25:19-26

The word Grandmother is in the Bible only once. Who is the only Grandmother specifically in the Bible?