How secure is title of house after quit claim in WA State?

My mother had a stroke 4 years ago and became partially disabled (mentally and physically). To care for my mother, I moved into her home and assumed responsibility for all affairs. Her home was paid for so there was no mortgage and my mother owned the title. To eliminate her assets and qualify her for Medicare and in-home care, my mother signed over a deed for property she owned (1 acre with no home) to my brother. Two years after her stroke she quit-claimed her home to me qualifying her for COPES and Medicare. Four years later I'm still taking care of my mother and the home. Now, my brother wants to be on the title of the house claiming it’s what my mother would have wanted. I want to settle with him some cash amount I deem fair after my mother has passed. He's married with children and I'm single. Can my brother take me to court and get his name forced on the title of my house? How secure is the title in this circumstance?