I would not force the naps if it is causing so much upset. It's not worth it. My son stopped taking naps at about age 3.5. It just go to be too much of a fight, some kids like their naps and willfully take them, while others don't do it so easily.
She sounds like a high intensity child and I'm sure it's not easy for you at your ages to be dealing with this, but I think it's great you are concerned enough to post. I';m sure her parents appreciate your help too.
Is she kept fairly active during the day?
I can remember at three my son having tantrusm, even at 4 and five. Not so much now at 6.
My son used to hit a lot when he did not get his way and he would get angry too. Still does to a point, but it's lessened a lot. He hits much less, thankfully... He's six though.
My son has sensory processing disorder. YOu can look this up on the net, see if it fits your granddaughter. She might just be going through a phase, hopefully that will go quickly.. Some kids do have long tantrums. Have htey talked to their child's pediatrician?
no I dont think it is a sign of abnormality but her parents could take her and get it checked out.Many children do not want to nap after 3 year old , so to try and make her is causing some trouble .Why do you feel shes needs a nap when in fact she is saying she doesnt need it ?