I am caring for my 90 year old Grandmother and her own daughter does nothing but nothing. Can I seek POA?

Your grandmother must initiate the whole process. It would not be good for you to just make an appointment with attorney and tell your gmo that she is going to assign POA to you. Its fine to talk to gmo about the issue, and tell her she has options, but it would be wrong for you to try and influence her decision. This is because, if you already have a close relationship she will likely put more stock into whatever you say--so you will automatically be scrutinized as having taken advantage of her friendship & trust. Whatever you do, if allowed by your state statute, voice record or even video tape your conversations with her, so that any one would see she is of sound mind, and also that you are not pressuring her to make you POA.
It could be that she would rather not have you as her POA.
And remember, once she dies, the POA ends. So if you're concerned about other relatives or friends abusing her property (money, car, home, deciding where she lives) before and after she dies, what GMO needs is not just the POA but an Executor.
Also she needs an Medical POA to make decisions if she is not able to communicate, such as end-of-life decisions.

Kimberly, are you saying that your Grandmother's daughter has Power of Attorney at this point in time? If not, who does? If no one has it, or your Grandmother wants to change the appointee, like JoAnn above had mentioned, as long as your Grandmother can still understand how a POA works,  she can appoint you.

As for the POA, it is best that you take Grandmother to an Elder Law Attorney to have the POA drawn up. And while there, if Grandmother's Will is quite old, she should update it to match current State Laws. The Attorney might even recommend a Medical Directive which is a guide line on what to do if Grandmother is unable to think for herself.

As long as GMom is OK mentally she can assign you POA for financial and medical.