How do I deal with my mom? She is 77 and she feels that all my siblings are out to get her.

How do you deal with WHAT exactly about your Mother?
Does your mother have dementia?
What does your mother have to do with your brother?
Need details.

Hi Janey & welcome! What medical conditions does mom suffer from? Does she have dementia that makes her paranoid & thinking that that your siblings are out to get her? My condolences on the loss of your brother.

We can't help you with a question that's put entirely into a title. If you give us more details & fill out your profile, perhaps then we can better understand the nature of your situation & offer comments that would be helpful.