Can I handle my mother's finances and not upset my siblings?

My mother is on hospice and has maybe one month left to live. I am the youngest of three children. My mother and I have always lived close to each other, spent everyday together and are best friends. I have been her primary caregiver for a couple of years now. Because of my relationship with my mother, my brother and sister have had tremendous jealousy towards me. They have never helped take care of my mother except when it was convenient for them nor have they made an attempt to have a really close relationship with her by telephoning regularly or visiting. Now, all of a sudden, they are both making a mad dash to make up for lost time and try and resolve any issues they may have with her, which is too late now because it is almost impossible for Mom to talk. My mother had asked me to take over her finances but I knew it would cause a problem with my siblings so I never did it. After my mother told my sister that she asked me, my sister jumped right in and started to do the bills. However, she was caught stealing money from my mother so my brother and I took that responsibility away from her. Because of the lack of trust between the siblings my brother and I were going to hire an accountant to take over the finances. It was even my brother's idea and we interviewed an accountant. Now my brother is saying he does not want to hire an accountant and that he wants us to do it. I just found out from my sister that my brother is so short on cash that he wants to write himself a check for $4500 and asked my sister and me to do the same. I have always promised my mother that I would take care of her and watch out for her best interests, not to mention to honor her last wishes. I told my sister that no, I would not write myself a check and that I did not think they should. My mother has only been given about two more weeks to live and they already want to start taking her money without her consent and now I am the one standing in their way of getting what they want. What do I do? I want to go right to the accountant on Monday and hire her and give her my mothers important papers and checkbooks. I will do anything I can to stand up for my mother because she can not do it for herself. I am afraid that it is going to be two against one. What should I do?