Changing the definition of full-time hours to 30/week would do far more for families and children than giving free childcare so mothers can work more.
Making mortgages with a > 20 year term illegal, putting limits on the total principal allowed to loan as a multiple of income, and barring entirely non-human (i.e. any business entity) ownership of single family homes would do far more for families and children by removing the burden of ridiculous housing costs by removing the ability for people to compete for ridiculous housing prices.