What to do if suspecting elder financial exploitation?

My grandmother has a mild case of dementia, and my family has been taking care of her the last few years since my grandfather passed. There are 4 children, one aunt is the power of attorney and the other aunt deals with medical side of it. The aunt that deals with the medical side, actually got her hands on the finances and bank accounts since my other aunt lost her husband. My other aunt is very laid back, and just somewhat goes with the flow. Now back to the other aunt, she was NEVER close to her mother, AT ALL. Literally acted as if she hated her and only would act nice to my grandfather. Since his passing a few years ago, I mean literally within a week after, all of a sudden she's acting like she loves and appreciates her. This is when she intervened herself into trying to be POA, to which my grandmother passed it to the other daughter. She also NEVER would spend money (because she didn't have it), the literal definition of a penny pincher. She wouldn't spend money on anything, or her children hardly, and basically made them work during high school to pay their own cell phone bills and so on. They rarely went on vacations, to restaurants or updated their home. It once took them a year to come up with the money to fix their air conditioning unit because she wouldn't do it, nor did her husband have a high income. She also does not work.
Well, after a series of events, she was sneaky and tried to cash a check for my grandfather's company right after he died, which was $30,000, that was missing for a few weeks. My parents found it with a forged signature and snagged a photo of it and gave the check over to my grandmother who had been looking for it. She's also hidden all sorts of other checks and so on and so forth that we cannot find, but she states she put into the bank account (that was the only one we had proof she forged her dad's signature). The siblings called family meetings to ask her to produce the finances multiple times over the last few years, to which she cries and says "why would you do this to me?!" and turns to my grandmother exclaiming, "you're going to die soon, you're sick blah blah blah.." She's also admitted to going to the grocery store & spending the money when buying both of their groceries. Now, most of my family is kind of onto the antics due to the excess amount of money she's ideally spending. She's out partying almost everyday, going away for long trips and vacations, remodeling her house, getting a new vehicle every single year and eating out every single night. She won't even let my grandmother see the bank account, who has noticed her spending habits over the past few years, to which she claims her husband got a job promotion. She also tells my grandmother that my grandfather left her with literally nothing every single time this comes into conversation, which we all know to be untrue.
My grandmother deserves better than this, she has done nothing but give her whole life and she seems distraught time and time again after her saying she has literally nothing, with my family attempting to convince her otherwise. We are worried that my aunt will use all of her money that she needs to live on the rest of her life, and that in the end, something unfortunate could happen to her financially and we don't want to put her into a home by reporting this to the authorities. My family is almost afraid to report her for this, although I am not. I am close to my grandmother and it sickens me to see such injustice daily. I've attempted to research ways to see if the bank can give one of the siblings a bank statement, probably my aunt, however I don't know that she will do to her avoidance to confrontation.
Also, my aunt used to do a lot for my grandmother like bring her to the doctor/shopping and now she hardly goes over there at all. Mostly because we've been pretty dormant about asking her about it the last 9 months. I am so worried for the wellbeing of my grandmother.

Is there another way to get a bank to look into the statements or give us a copy without me having to get one subpoenaed?
Will my grandmother have to go into APS and be removed into a home, although she has three other kids that provide for her?
What are our options?

Thanks for any insight you can provide!