H4(Child) - US Visa DropBox

My Dependent Spouse and kid(more than 3 years Old) are traveling to Indian alone and Our Visa stamping has already been expire in last 31 Dec 2018. Please confirm if they(spouse and Daughter) can go DropBox.

Note - i heard from one of my friend that if both parent (Father and mother) have valid US visa stamped then only your child can have eligibility for US Visa DropBox. please confirm if anyone have same condition .

No, for child, it is their age. If they are under 14 years of age, they are eligible for Dropbox. Check Official US Visa Dropbox Guidelines