Who's asset is the trust?

My father placed a building he owned and rented in a trust and named my brother trustee. All rent receipts supposedly went into a checking account for my mother which was also in the trustee's name, to take care of her and maintain her home, taxes, etc since she could not balance a check book. The house and car were left in my mother's name. She passed away on 3/26/20 with no will. I received a letter from my brother's lawyer stating " the only assets of the estate are your mother's house and car. Her bank account was held jointly with Bob, so it does not need to be released by the court." I have not seen paperwork on the trust and my father left no will. My brother wants to be named commissioner to handle the paperwork, title the house and car in my and my sister's name, and divide the funds among the three of us. Doing this, does the trust, building and bank account, become my brother's alone?