The estate's tax exposure is set at the moment of death, using the home's fair market value then, and again at the moment of sale, using the sale price. The difference between those two figures, less selling costs, is the gain the estate reports, not something each heir calculates separately on their own return.
Disagreements tend to surface among heirs when that date-of-death value feels arbitrary rather than documented, since a low number understates the estate's tax owing while a high number can look like it favours whoever wants a quick sale. A written, defensible valuation heads off that suspicion before it becomes a dispute.
Every estate should confirm its specific filing obligations with an accountant rather than relying on a general answer. Get your hand-reviewed valuation from Joel Dyck.