RTA investigations involve a specific team and standardised procedures: it's hard to believe they weren't followed when two children died, meaning there would be intense public scrutiny.
The driver doesn't need to prove anything, but also would be unwise to speak publicly about what happened, in case of prejudicing any court case.
The job of the prosecution would be to prove beyond reasonable doubt that the driver was asleep/drunk/drugged/using her phone/speeding/driving in contravention of medical advice/acting maliciously/carrying out a manoeuvre unforgiveably badly. They don't have to prove that she doesn't have epilepsy.
People do have one-off fits, or faints, but the physical evidence can differ depending on whether the driver is conscious.
If there's a trial, and she's found not guilty, the surviving victims could still sue for damages, because the standard of proof is much lower.
The only new information is that the police are accused of providing false or misleading information to the surviving victims. This is intriguing.