Let's get this into perspective. This lady would almost certainly have been charged with causing death by careless driving. The death does not make the driving dangerous rather than careless. It is purely the manner of driving which determines dangerous or careless. The descriptions I have read of the incident would almost certainly not support a charge of dangerous driving.
So, that said, she would be sentenced in accordance with the guidelines for that offence. These are here:
https://www.sentencingcouncil.org.uk/offences/magistrates-court/item/causing-death-by-careless-or-inconsiderate-driving/
This was not (again, from the reports I have read) "a prolonged, persistent and deliberate course of very bad driving"; no drugs or alcohol were involved; no mobile phone usage was involved. From what I have read (and I do know a little about sentencing for such matters) the driving itself would be seen at the lower end of seriousness and so a custodial sentence would be unlikely. Even if it was imposed, it would almost certainly be suspended. So let's step away from the idea that this woman would have been led away in chains for a lengthy spell in the chokey. It was never likely.
I agree she should not have fled the country. But I think the Dunn family need to accept that she did and they probably would have been more disappointed had she remained and been given six points on her licence and 40 hours of unpaid work.