Tenants are more aware of their Section 8 vouchers than their own children. 

The only exception I make is adult children, who are still screened, but not named only as occupants on the lease. 

Families with young children may not be interested in such flooring out of fear of a child getting hurt.

Any recommendations for an affordable gardener/landscaper who could do a clean-up to make it safe for the tenant's children?

How can we save our futures and children?

My children would definitely love that.

Low to very-low incomes, most children in school receive free meals, high crime rate, and on top of that there are 104 registered sex offenders living in that zip code.

The rule is in place largely to discourage family sweatheart deals where say, parents want to make interest free loans to their children.  

Has grown children, but they are special needs(?). 

If something happens to husband of couple B, they will be out of income and may not sustain, plus they have children that will be their priority (I.e. not the rent.)Best indicator of tenant willing and capable of paying rent is the credit score.