In the Name of Allah, the All-Merciful, the Mercy-Giving

All praise is due to Allah. Peace and blessings be upon his Messenger.

If a woman becomes clean of her menstruation before Fajr Prayer, she has to perform ghusl in order to pray Isha’ Prayer. According the majority of scholars, she has also to pray Maghrib before Isha’. This means that performing ghusl becomes obligatory at that time to catch both Prayers before Fajr time.

Sister, you have provided no reasonable justification for your apprehension of taking bath at night. I advise you to read the Qur’an and seek refuge with Allah from the whispers of the Satan. It is the Satan’s job to bar people from worshipping Allah by casting such unreasonable fears into their souls.

Allah Almighty knows best.