Should a president die in office, which official succeeds the president if the vice president is unable to assume the role

If the President dies in office and the Vice President is unable to assume the role, this is assumed by the Speaker of the House of Representatives.

Explanation:

The Speaker of the House is the presiding member of the House of Representatives. Under the United States Constitution, the Speaker of the House is the second person after the Vice President to replace the President if he is unable to exercise his office, for whatever reason. The Speaker does not supervise the ordinary meetings of the House; his role is more or less administrative.   The current Speaker of the House since January 2019 is Democrat Nancy Pelosi.

sorry i cant