As you know, Frieza was transformed into a cyborg. Before that, he created an egg containing all his emotions and hate toward the saiyans. The egg needed a lot of time to grow(like Cell) and by this time, all the old Z Fighters were dead. -name- emerged from his sleep. He still felt a huge hate toward the Z Fighters and learned they still had descendants. Then to exact revenge upon Frieza's death, he will attack Earth.
Feel free to use it or not :)