Are They Sinful? Will Allah Hold Them Accountable?

Assalamu alaykum, I really need some guidance on something heavy. My cousin, she’s just 25 and the only sister among four brothers, got diagnosed with a serious kidney disease back in 2023. At that point, a transplant could have saved her, but it meant finding a donor and coming up with a lot of money fast. Her brothers refused to give a kidney, saying they couldn’t risk having another sick person in the household. They talked about finding a donor from outside, but they never sold any property or made real financial sacrifices to make it happen. They kept saying they were gathering funds, just waiting, but honestly they didn’t even bother looking beyond local doctors or leaving their city to explore better options. It was all talk. Now her health has gotten so bad, she developed heart failure from fluid buildup, and she’s no longer eligible for a transplant-she’s terminally ill. I think she might have a year left at most. I feel this burning resentment because I truly believe she could’ve been saved if they’d stepped up. They do take her for dialysis and some palliative care, but I see them acting tired and frustrated, then pretending everything’s fine. Maybe it’s denial, or they’ve just accepted it, or maybe they never really cared enough. The money they said they were saving for her transplant? They ended up buying properties with it and even brag about that. I’m struggling here: Islamically, did her brothers have a duty to donate a kidney or sacrifice financially to get her treated? If they had the means but deliberately dragged their feet or didn’t try hard enough, are they sinful? Will Allah question them on the Day of Judgment? And am I wrong for resenting them and judging them so harshly? Sometimes I just imagine myself screaming at them, arguing, I don’t even know. I’d truly appreciate an Islamic perspective on this. JazakAllah khair.