We believe that our step brother is abusing our mother's financial left by his dad when he died. His dad made sure he had all the power. They threw mom in a nursing home, and continue to live in her house until she dies. They have moved the entire family in, and use moms money to pay all the bills. He will not provide any proof of how he spends her money. They take elaborate trips, and have the best of everything. When we ask for a financial accounting of her money, he refuses and says we are contesting her will and will make sure we get nothing and he gets everything. We think this is elder financial abuse. Is this contesting a will while she is still alive? We believe that this is elder financial abuse fueled by their greed. This is in Washington State.
Second, what is your source? Is it on "information and belief", supposition, or based on what? What documentation do you have?
Third, from what you write ("step dad made her will with his"), the Will was joint. Was your step father's entire estate inherited by your mother when he died? Do you know if there were any assets he held that she didn't, and weren't inherited by her?
And do you know specifically what he left for your mother?
Fourth, you wrote the stepbrother/family "use moms money to pay all the bills. He will not provide any proof of how he spends her money". How is it that you know your mother's funds are paying "all the bills" w/o having any proof?
Fifth, and I don't know the answer to this specifically as I don't remember how joint Wills are handled in probate (maybe someone else here does), BUT, if your stepfather made specific bequests in his will for your mother's care, and if your mother's care is the subject of an ongoing care provision in their joint will, you might be able to contest the administration of your step father's portion of the Will. This is definitely a question for an attorney.
I'm not questioning your interpretations, but you're going to need documentation to support the accusations you're making.
Because of this and b/c your mother, as remaining testatrix (person who makes a will) is still living, and b/c she has Alzheimer's, you really need an elder law or estate planning attorney with experience in probate litigation to help sort this all out.
You could look for one in Hawaii, and that person would generally hire a local Washington attorney. The two then work together.