Temporary assistance for needy families grants shall be made to persons specified in RCW 74.12.010 as amended or such others as the federal department of health, education and welfare shall recognize for the sole purposes of giving benefits to the children whose needs are included in the grant paid to such persons. The recipient of each temporary assistance for needy families grant shall be and hereby is required to present reasonable proof to the department of social and health services as often as may be required by the department that all funds received in the form of a temporary assistance for needy families grant for the children represented in the grant are being spent for the benefit of the children.