I've very mixed feelings on this case and I doubt that I or anyone else pontificating about it has sufficient knowledge to make a judgement.
A woman died tragically and unnecessarily. She did not cause her own death, nor did the unfortunate woman who hit her. I don't think disability should be a (literal) 'get out of jail free card'. The sentence per se doesn't seem unduly harsh either. Maybe the issue is where Ms Grey serves it, and what provision there will be for her housing when her sentences concludes?
Read about another case today - name escapes me, but a 22 year old man was killed and left dead in a ditch by another 22 year old driving a BMW without insurance. He had also been banned from driving. He left the scene, and the young man's mother was left to find her horrifically injured dead son via tracking on his iPhone. Sentence - 7 years!!! Such a travesty.