After my father unexpectedly passed, I became the guardian and POA for my aunt (we live in Illinois). I have had to make trips to the care facility, to lawyers, and to financial institutions. All of these are a few hours away. What is the right IRS mileage rate for reimbursement - is it the medical rate or the business rate? I am not taking a stipend or any other payment.
Given that you have a mix of what you consider both, it would be helpful to become very familiar with the criteria for both medical and business mileage rates. You might also do some research to confirm that you can charge for trips to financial institutions and legal offices - just to be on the safe side.
Or, since you're guardian, there might be a court established mileage rate. Check with whoever you're in contact with, or report to, at the court.
Pam Stegma has experience in guardianships; if she sees this post perhaps she'll offer advice.