From all the OP'd posts her DS is happy and healthy. He goes to school. He eats. He sleeps. She looks after him and his needs first.
Also why would DHS take her son away if he is happy, healthy and unharmed? They are there to help support families and will only remove children if they are in danger.
There are times when there are dishes piled up in my kitchen. And there are barely clean clothes. Does that mean that I am a bad mother?
In this situation her mother is supposed to look after her son's wellbeing while she is unable to - which is after treatment. So technically her mother is neglecting her grandson - it is not her.
OP - what is your son's current 'currency'? The reason I ask is because I know he won't just help himself to food but maybe he kight make something you prepared if you tell him he needs to eat before he gets to play/do x.
Also hugs. Congrats for your son's scholarship!