My brother seems to have abducted my mother and is mistreating her at his house in Kansas. My mother is 74 yrs old and I'm all the way in LV.

If you have cause to believe your mother is being abused call Adult Protective Services in the county where your brother lives and report the facts as you know them. If you believe she’s in imminent danger, call the local law enforcement and request a wellness visit for her at his address

What is your actual question? We need much more info from you: Does your Mother have a cognitive/memory issue and/or other medical problems? How do you know he is mistreating her? Are you communicating with her? Who is the PoA for your Mother? Is anyone?