Does my blind friend need a will'

This widow is in her early 70s and is totally blind. Income old age pension or similar public program. She hos no children and a couple of out of state sisters. She lives in a rented apartment and does not own any real estate. Other than personal items such ad clothing and furniture, her only possession of value is an $800 electronic piano. Does she need a will? If so, what would it cost to have one? She already has a DNR document. Guidance will be appreciated.