Does Medicare cover in-home care and how much does it cost?

My husband has heart problems, falls a lot, has kidney and other medical problems. He is unable to bathe, do his medications, cook and walk any distance. I take care of these things now but should I get ill or for any reason be unable to do these things, he might need someone to come in and stay daily to help him. Does Medicare pay for this and should I just need assistance how long and how much is my cost?