回复：母亲签证

Use H4, you need to send your parents a copy of your passport, visa ...

Write a polite letter and explain why your parents were refused for a visa before and this time you still want to invite them to come to see your family and look around USA, write a detailed travel plan, that will really help a lot. Indicate that you will cover all their cost in USA that includes travel, food, medical insurance, etc ...

DO NOT mention your child is in China, that will do harm rather than help for their application