Of one mother - Israel and Judah were branches of the same stock.

Son of man, there were two women - All the Hebrews were derived from one source, Abraham and Sarah; and, till the schism under Rehoboam, formed but one people: but as these ten tribes and a half separated from Judah and Benjamin, they became two distinct people under different kings; called the kingdom of Judah, and the kingdom of Israel. They are called here, because of their consanguinity, two sisters. The elder, Samaria, (for there was the seat of government for the kingdom of Israel), was called אהלה aholah, "a tent." The younger, Judah, was called אהליבה aholibah, "my tent is in her," because the temple of God was in Jerusalem, the seat of the government of the kingdom of Judah.

Son of man, there were two women, the daughters of one (a) mother:
(a) Meaning, Israel and Judah who both came out of one family.

Son of man, there were two women,.... Or two nations and kingdoms, the kingdom of Israel or the ten tribes, and the kingdom of Judah or the two tribes. So the Targum,
"son of man, prophesy concerning two provinces, which are as two women:''
the daughters of one mother; either Sarah the wife of Abraham, from whom they sprung; or because they were originally one kingdom and nation; so they were when they came out of Egypt, and during the times of the judges, and in the reigns of David and Solomon; but became two in the days of Rehoboam the son of Solomon, from whom ten tribes revolted, and set up a separate kingdom, with Jeroboam at the head of it.

ISRAEL'S AND JUDAH'S SIN AND PUNISHMENT ARE PARABOLICALLY PORTRAYED UNDER THE NAMES AHOLAH AND AHOLIBAH. (Ezekiel. 23:1-49)
two . . . of one mother--Israel and Judah, one nation by birth from the same ancestress, Sarah.

Two women - Judah, and Israel, two kingdoms.