How do I go about to getting power of attorney?

You don't. You've missed the boat. Power of Attorney is given by a person while of sound mind to a person whom she trusts to act for her once she is no longer able to act for herself.

And who's this "we" who wants to change your mother's will? You do realise how incredibly wrong that sounds, do you? The only person who had any right to alter your mother's will was your mother.

If you need to act for your mother to protect her, you will need to apply for guardianship. You still won't be able to change her will though.

Her existing Will should govern, unless she was not competent when she signed it. I'd see an attorney if that is the case, but, you can't just decide to redo it or make a new one, if she is not competent to make her own decisions.

I wouldn't have hope of getting a POA either, if she's not competent. An attorney will have to take measures to ensure that she understands her POA appointment and is competent to sign one.

If you need authority to act, I'd see the attorney about Guardianship, if the POA matter can't be resolved.

No, you cannot make changes to a pre-existing will using power of attorney, especially if it benefits the person who holds power of attorney. A person has to be "in their right mind" or "competent" to execute a power of attorney legally. If you need to get a legal right to act on mother's behalf, you will need to seek guardianship through the courts. Sorry, but the laws were put in place to protect individuals, sometimes to a family's dismay.

Sorry, Bobby, only Mom can appoint someone to be her Power of Attorney, and only Mom can make changes to her Will.

Since your wrote that she is not in her right state of mind, no Attorney would even consider having Mom sign any type of legal documents.