Providing Rational Options Toward the Elimination of Catastrophic Terrorism Act of 2021 or the PROTECT Act This bill directs (1) the Department of Homeland Security (DHS) to develop and provide guidance on terrorism preparedness and response to assist in the development of plans for addressing active shooter and mass casualty incidents, including in facilities identified by DHS as vulnerable targets; and (2) the Federal Emergency Management Agency (FEMA) to consider the threat from active shooters in allocating grant funds under the Urban Area Security Initiative and the State Homeland Security Grant Program.