Ben and Vestara managed to kill one avatar of Abeloth at the Font of Power
Krayt and Luke killed her at the Lake of Apparitions.
Abeloth was able to overpower both the Son and the Daughter at the Font of Power, which I belive is some sort of force nexus? Before the Father stopped her.
Later the siblings used the Killiks to imprison her and would return to the galaxy whenever she needed to be stopped again. That is ouf course until Dumbfuck Skywalker decided to kill off the literal gods so he can sleep with a senator.