All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
It is permissible for the woman to enter the mosque at any time provided that she is not in her menstruation period, in a major impurity, or in the confinement period. In such states, she should not enter the mosque unless she becomes pure. Allah Says (what means): {O you who have believed, do not approach prayer while you are intoxicated until you know what you are saying or in a state of janabah, except those passing through [a place of prayer], until you have washed [your whole body].} [Quran 4:43]
The wives of the Prophet used to visit him while he is in I’tikaaf in the mosque. It is also narrated in a sound Hadeeth that he said: “The best rows for men are the first rows, and the worst ones are the last ones, and the best rows for women are the last ones and the worst ones for them are the first ones.” The Prophet made it clear in this Hadeeth that women could participate in congregational Prayers in the mosque. The Prophet even ordered men not to prevent women from going to mosques if they ask their permission.
For more benefit on women praying in the mosque, please refer to Fatwa 82359.
Allah knows best.