Here are some Jain-friendly girl names starting with M, with simple meanings:

• Madhavi — spring, sweetness; a gentle, blossoming name.
• Madhuri — sweetness; a lucid, pleasant name.
• Manavi — of the mind; thoughtful and humane.
• Manasi — born from the mind; calm and reflective.
• Maitri — friendship; harmony and cordiality.
• Meera — devoted, faithful; commonly used in Jain as well as other traditions.
• Mahika — earth; grounded, natural (a grounded, strong presence).
• Mohini — charming, enchanting (note: widely used across traditions; usage varies by family).
• Malini — fragrant, garland-like beauty.
• Mridula — soft, gentle; tender-hearted.
• Mihira — sunbeam; bright and shining.
• Mila — affectionate, loving; a warm, friendly name.

If you’d like, tell me any preferences (length, meaning, traditional vs. modern, how it sounds with a family surname), and I can tailor the list further.