PATH Fairness Act of 2017 This bill amends the Public Health Service Act to revise and extend Projects for Assistance in Transition from Homelessness, which provide services to individuals who: (1) are suffering from serious mental illness, or are suffering from serious mental illness and from substance abuse; and (2) are homeless or at imminent risk of becoming homeless. The minimum allotment of program funding for each state and territory is increased on the condition that appropriations are sufficient to provide the minimum allotment to all states and territories.