if someone is in the nursing home can family go against the will

A will only has legal effect after it is admitted to probate and then only with regard to the property which passes under the Will.  If the house has been sold, it will not be part of the estate which passes under the Will.   The agent under a Durable Power of Attorney has a duty to preserve the estate plan reflected in the Will only to the extent that that plan does not interfere with the person's need for care.   If the agent is selling the home to pay for nursing home bills, the agent is doing his or her duty.