It's really hard to say who the author might be without more information. It could be a relatively unknown fanfic writer who just came up with this unique concept. Maybe it's someone who has a personal connection to the name 'Chichi Goku' and decided to write a story about it.
Perhaps in the fanfic, Chichi Goku was part of a group or a family where that name was common. But due to some events, like a falling out or a change in the group's dynamic, no one uses that name for them anymore. It could explore themes of isolation and the character's journey to either regain their old identity or create a new one.
Frieza's victims in the manga included many powerful fighters. For instance, he eliminated Dende. His actions were driven by his cruel and power-hungry nature.
Frieza turning good in fanfiction would be a major game-changer. It might involve a character arc where he realizes the error of his ways and strives to make amends, adding depth and complexity to his persona.
Well, Vegeta would be a likely character. He might be initially suspicious of the female Goku. Maybe he thinks she's a threat or just can't believe there's another Goku - like being. He could be there to add some comical moments as he tries to understand the situation.