Other than claiming the medical expenses, there are no additional tax credits available to your sister for your mother.
There are disability/medical credits on both the federal and Oregon tax returns, but they can only be claimed if your mother files by herself.
For more information about claiming an elderly parent, follow this link:
https://turbotax.intuit.com/tax-tips/family/steps-to-claiming-an-elderly-parent-as-a-dependent/L34je...I am sorry your family is facing such a difficult time.
