If she leaves the US while her case is pending it will be considered abandoned.

Your friend should apply for a visitor visa on his own by establishing sufficient familial and financial ties to his home country.

Husband on H1-B has abandoned me, I suspect its a case of cheating,what legal actions can I take against him to get justice?

You can apply for divorce and terminate the marriage. Consult with an attorney for further guidance.

My mil is sick and her visitor visa is expiring in October, she is not in position to travel, is there a way to extend her stay?

Yes you can extend her stay based on her medical condition and by submitting evidence of her current condition.

Why deferred action was approved in 2017?

The EAD processing depends on when the application was submitted. Consult with your attorney for guidance.

U visa - Deferred Action was approved in 2017 and processing was done by March 2018. How long we have to wait to get EAD?

You should consult with your hired counsel for assistance with case specific inquiries.

I-485 PART 5

It appears that yes you are applying together. Consult with an attorney for further guidance.

Would we be to late to file form I-751? How long does it take to process?

You should file ASAP before the expiration of the CPR.

Using solely saving as proof of financial status in sponsoring spouse greencard application

In addition to the use of assets, you can also use a qualified cosignor to fulfill the financial support obligations.

Change of Green card address?

You can file AR11 for change of address. For your other questions it is best to consult with an attorney in private.