8.0 speculation

[Cilia]

Must have missed or forgot about that one.

Sidequest chain "Stranded at the Station" --> "Mum is the Word."

While there is no hard confirmation, you find a royal guard and chambermaid who fled with the royal family (including Nerva and, presumably, Titus) when they came under attack by Anima's thralls and rogue warmachina; they fled from Senaculum Imperialis to Palatium Novum, but you find no other survivors beyond the royal guard and chambermaid in question. The implication is that they were the only survivors.