As caregiver for my 91 yr old aunt, should I have "end of life" legal power if she gets sick?

Does anyone have medical power of attorney (medical proxy) for her now? Does she have an advance health care directive? If she is of sound enough mind to understand the concept of having someone make medical decisions for her if she becomes unable to make decisions herself, then it is a good idea for her to name that somebody. It should be someone who would be able to respect her wishes even if they don't agree with all of them. Sooner is better than later to get this taken care of!

I don't know, you haven't given us any information.