You have indeed been a member for a while, my apologies. As you have done your research on the possibiity of your friend getting DLA for PND, I'm not sure there's a lot I can add.
DLA is for help with personal care and mobility, as I'm sure you know. It's impossible to say, so if your friend needs other help she may qualify. On the cooking test for example?
She could submit a claim, a long shot maybe but there's no harm in trying. Then again I know how awful the forms are to complete.