My Dad is 87, living with my sister and I believe she is squandering his money. Any advice?

You start by talking to his doctor about what type of care he needs. The MD will also be able to put you in touch with agencies in Dad's area.
As for your sister, the next time she says she's suicidal, call her police department and ask them to check the welfare of your father and her. They can cart her away to rehab and they will take care of Dad too.

Most communities have human services agencies that may be able to assist you. To find out what your father’s community has to offer, contact the Eldercare Locator, 800-677-1116, sponsored by the National Association of Area Agencies on Aging. Another source is your father's state Department of Aging or county Area Agency on Aging. These government-funded agencies will know what services are available in their area. There are websites available that provide information about local services and quality care. If you don't know how to find them, go to your public library for help on locating services to help your father.

Many local resources are also listed in the telephone book. Yellow pages list businesses and nonprofit organizations under many categories. Resources may include independent services, and some hospitals, that have outreach programs to go into private residences to help with daily activities such as cooking, cleaning, personal hygiene, bill paying, and other paperwork. In some communities, volunteers, such as students and members of religious organizations, perform these kinds of services. Organizations such as Meals-on-Wheels also can help you care for your parents in their home. The blue pages, available in some telephone books, list federal, state, and city government offices that may also provide information.