The Abacha regime oversaw the termination of Ernest Shonekan's government.
Ernest Shonekan was appointed as the interim head of state by Ibrahim Babangida, who had stepped down from power in 1993. Shonekan was appointed with the mandate to organize new elections and return Nigeria to civilian rule. However, his government was short-lived as it was overthrown by Sani Abacha's military regime in November 1993, just three months after his appointment. Abacha assumed the position of military head of state and dissolved all democratic institutions, effectively ending the transition to civilian rule.
Therefore, the correct answer is Ernest Shonekan.