Are there agencies that take Medicare?

If you're wondering whether Medicare will pay for homecare, generally no. Not long-term. They will provide limited homecare after hospitalization and/or surgery. Also they pay for hospice in-home care. For long term care, you need to look to your state's Medicaid program.

Medicare is a Health insurance. They will pay for short term rehab and homecare usually associated with physical therapy or woundcare. But that is also short term. Medicare does not pay for caregiving longterm.
Medicaid may help if person is low income a few hours a day. But not usually 24/7. Though, some states do seem to offer a program to keep people in their homes. But agencies usually are private pay. You would have to contact Medicaid in ur County to find out what your state offers.

Are you sure Medicare will pay? Your post has home care tagged. If the person needs home care, it may not even be covered by Medicare.

What agencies are you referring to. Need to be more specific.