Mahavir Swami’s mother is:

• Queen Trishalā (Trishala Devi / Rani Trishala) – wife of King Siddharth of Kundgram (near Vaishali).
• Jain scriptures also describe a divine event called garbha-parivartan (embryo transfer):

- The soul of Bhagwan Mahavir first entered the womb of a Brahmin lady Devānandā. - Then the devas transferred the embryo into Queen Trishalā’s womb, so Mahavir was finally born and raised by Trishalā. - Because of this, Devānandā is remembered as the biological mother, and Trishalā as the mother who gave birth and brought him up.

• Both Digambar and Shwetambar accept Queen Trishalā as Mahavir’s mother; they differ mainly in details like number of auspicious dreams (14 vs 16), not in her identity.

You can read a simple life story of Bhagwan Mahavir and his parents here and about Mata Trishalā and Devānandā here