Dying at home without being under a doctor’s care for some malady is not grounds for an autopsy in the state of Tennessee. It may be in other states, but I would be suprised if it were more than a handful.
It may be different in Tennessee, but how would they know the person had a malady unless they had seen a doctor within a certain amount of time?
"Generally in the U.S. autopsies are performed when there is suspicion of foul play, when there is some public health concern, like a mysterious disease, if someone dies unattended by a physician, or if the attending physician is uncomfortable signing the death certificate."
"Even if none of these conditions apply, the next-of-kin can request an autopsy. If an experimental treatment was being used, if a patient dies unexpectedly during a procedure that is rarely life-threatening, or if there are concerns about genetic implications, the state or the next-of-kin may decide to request this. An autopsy may also be performed when there are implications affecting insurance payouts." "Individual jurisdictions may have additional circumstances in which an autopsy is required. Some religious groups are opposed to autopsies and some require that a person in authority from that religion is present during the proceedings to ensure that their religious tenets are not compromised."
The above was taken from here: Under what circumstances is an autopsy carried out?