Well, I'm not in the Nursing field, but... I can definitly see that being a violation. When you accept a position providing in home care, or a health care provider offers in home care, either the both of you accept that responsibility of getting yourself there, or someone within your company getting you there, or you hire attourneys that can construct a waiver of privacy due to unforseen circumstances such as weather. If the person you are caring for is that ill that they could not be without in home care for a day, or two, then they would have to realize there may be the need for alternative transportation for the care provider, and it might risk privacy.
Then again, the provider should have a plan in place when a particular person cannot make it to the patient.