How do I get my mother’s benefits changed over after she moves from another state?

Lilliput had amazing answers as always! MyMedicare.gov will be a good start for the Medicare insurance changes, but you'll have to contact her supplementary insurance and Medicare D (prescriptions) separately, most likely.

It's a lot to do - all of the things we've mentioned - my heart is with you. You'll get through it one day at a time.
Carol

You need to contact each company/agency and ask how you do a change of address. Everyone has their own rules and forms.

I opened up a bank account for Mom where her checks could be direct deposited; and I pay her bills online too. It is a real time saver.

Also, contact the IRS and download form 8822. Once they have changed her address they will contact Social Security and change her address automatically.

Go online to the USPS website and change her address to yours now. You will start getting her mail and that will help you figure out whom else you need to contact (like insurance companies, lawyers, bankers, etc.).

good luck