There are many scriptures which say that Krishna went along with his wife Satyabhama. During the war, Krishna used his discus to kill Narakasura. I have heard another theory that Narakasura had a boon that only his mother can kill him. So Bhudevi took an incarnation as Satyabhama and killed him. Is there any scriptural reference for this?
Actually no , she aided lord krishna , but it was lord krishna in the end who killed narakasura.
https://www.sacred-texts.com/hin/m05/m05048.htm "Vasudeva, too, endued with all the divine attributes that ensure success, agreed to undertake that exceedingly difficult task. In the city of Nirmochana that hero slew six thousand Asuras, and cutting into pieces innumerable keen-edged shafts, he slew Mura and hosts of Rakshasas, and then entered that city. It was there, that an encounter took place between the mighty' Naraka and Vishnu of immeasurable strength. Slain by Krishna, Naraka lay lifeless there, like a Karnikara tree uprooted by the wind. Having slain the Earth's son, Naraka, and also Mura, and having recovered those jewelled ear-rings, the learned Krishna of unparalleled prowess came back, adorned with beauty and undying fame. "
https://www.wisdomlib.org/hinduism/book/harivamsha-purana-dutt/d/doc485605.html "Naraka’s head, cut off by the discus, appeared on the battle-field like unto a mountain of minerals clapped by a thunderbolt."
https://www.wisdomlib.org/hinduism/book/vishnu-purana-wilson/d/doc116051.html " and when Naraka came into the field, showering upon the deity all sorts of weapons, the wielder of the discus, and annihilator of the demon tribe, cut him in two with his celestial missile. "