How many days does one have to secure financing when attempting to buy the family house inherited by passing of parent when it is willed to more than.

There are two or three questions here.   First, is he entitled to live in the home rent free for 90 days or any other period of time?  No.   Second, how long after the court appoints an executor or successor does that person have to sell the home before the mortgage lender can foreclose?  Federal law allows six months.   Third, can the sibling set a 90 day deadline for a prospective buyer to obtain financing?  No.  The sibling does not even have the right to demand an accounting until many months (usually over a year) have passed or to ask the court to replace the executor until an even longer period (say, two years) has passed without the sibling having received a distribution (one quarter of the net sale proceeds of the home).  This is usually the same period which must pass before the sibling can bring a suit for partition, forcing a buy out or sale.