Can I Apply for GreenCard?

If the priority date is available on the I 140 yes you may go ahead and file. If you are talking about filing based on the marriage you need to...

Will my F1 visa Approval in my home country will get get impacted if in past I delayed in applyingfor COS (F2-H4 ) being in USA?

If you were out of status it may impact the F1. The decision is up to the US consulate.

Can a Green Card holder be out of state for more than 1 year due to COVID-19 and health problems?

Your mom should apply for returning resident status SB-1 with the US consulate.

If the LCA was incorrect it cannot be corrected. If the I 129 is incorrect you can try to have it corrected or you may need to re-file.

F2 status is dependent on the principal having F1 status. Once the F1 no longer has F1 status your F2 status ends.

What should I do in my situation?

Assuming you are eligible to file for adjustment of status simply file the adjustment package.

H1 and H4 both approval

Generally the last action approved is your status going forward. You need to have this matter resolved as you are likely to be considered in H-4...

What does USCIS mean by tax records when you have not filed taxes?

If you are not required to file taxes provide a statement that included the reasoning for your eligibility not to file taxes.

Interview Cancelled?

Since you are a resident status has been approved and you have a green card ignore the notice

How can I get child custody of my 2 year old son?

Moving to child custody thread........