I am 500 miles away, married etc....my unmarried, unemployed, homeless sibling, jumped in and agreed to care for our mother...Hospice comes in everyother day but for the past few weeks my mom is being left alone...day and night, eating cookies or crackers and begging me not to tell...I am so angry I feel like I may explode. My sibling is there to shower and hang out and off again as soon as the nurse is gone, I checked my mothers bank account and it is 50.00 overdrawn as of last week....I promised my mother I would let her handle this ,she has cried and begged me to say nothing...Is it awful to go against this promise, she may not speak to me again, but I can't set back and do nothing. I am no better by seeing and not doing , than the sibling acting like a teenager
Also, it sounds like you have some unforgiveness towards your sister that you need to deal with.
Go buy a plane ticket and go see your dying mother. Why you would think your brother would be an eligible candidate to care for your Mom is beyond me, given it sounds like he may have a track record of being unreliable - unless, of course, he's one of the causalities of the dire global economy decline many of us find ourselves in.