Is there really a mother God in the Bible/Christianity? What about these scriptures: Revelation-21:9-10, 22:17 and Galatians-4:16?
I assume you want the Christian answer to this question. Other religions do propose a mother goddess. This would include Mormonism and, in a sense, Hinduism. However, Christianity, like Judaism and Islam, is avowedly monotheistic. There is no mother goddess.
Besides, the Christian concept of God does not include gender. God is neither male nor female. “He” does not have sexual genitalia. We use “He” out of tradition, not because God is a male. God has the ideal qualities we associate with the female, such as nurturing, tenderness and the like, and God has the ideal qualities we associate with the male, such as strength and decisiveness. Of course, these are merely stereotypes, but Jesus had both categories of qualities in the highest measure. He had the strength of character and decisiveness we tend to associate with maleness, but he had compassion and tenderness in equal quantity. No, there is not a mother God.
In Revelation 21:9, the “bride” is the Church. It is clearly figurative, as is all nearly all of Revelation. It could be taken figuratively to be the Church or the City of God/Kingdom of God/The heavenly city and it is probably being used metaphorically to represent all three. The Church is called “the bride of Christ” in more than one place in the Bible. For example, there is Ephesians 5:25-26 which uses this metaphorical imagery for the Church. The bride in “the Spirit and the Bride say ‘come’” is, likewise a symbol of the Church or, more likely of the final Kingdom of God (heaven).
I assume your use of Galatians 4:16 was an error. Did you mean a different passage? I see nothing relevant to your question in this passage.