Sad case. I last did criminal law a long time ago, but in England, mens rea, or intention, is required to prove murder. Appalling though the behaviour of this woman was, unless she deliberately drove at the children, it would not be murder. We do not have degrees of murder. But In England the situation is worse, in one sense, since there is a specific offence of causing death by dangerous driving. The maximum penalty is less than for manslaughter, manslaughter is unlimited. Drivers are always prosecuted for the offence of causing death by dangerous diving. I never understood why. For reasons which are unclear, therefore, drivers who kill usually get a fairly low sentence.