Mother's Day Commemorative Coin Act - Instructs the Secretary of the Treasury to mint and issue not more than 400,000 $1 coins emblematic of the celebration of Mother's Day.
Authorizes the Secretary to issue such coins beginning on January 1, 2018, except that the Secretary may initiate sales of such coins, without issuance, before such date.
Terminates such minting authority after December 31, 2018.
Requires coin sales to include a $10 surcharge per coin, with distribution of one-half of such surcharges to the St. Jude Children's Research Hospital and one-half to the National Osteoporosis Foundation for the purpose of furthering research.