I suspect one of my siblings may be taking advantage financially of my Mother. Can I request a credit report on her?

You can only legally access her credit report with her written permission. I don't know what would happen if you accessed her credit report, found damning information, but hadn't gotten her written permission. She could turn the tables on you! Be careful.

If you have someone's social security number, full name and birthdate, you can get a credit report on line.

Does anyone have financial POA? Is mom still able to make her own decisions? If not, someone needs to get control of the money and cut the sib off. If you you can prove theft from an incompetent elder go to police.