The only additional thing that I would add to what has already been provided, includes that you should hire an attorney that is also a mediator.

Is this "contract" valid?

You likely have an offer, acceptance and consideration...ergo it's a contract

Can my step dad take an spend my social security check I get off my mom

Who is the payee in your family? What types of benefits are they receiving? SSDI...SSI?

Will he be able to come with her ?and if it is not possible can he come and wait here while her mother applies in his behalf?

Mr. Callan is correct, although you should send him additional questions via Avvo to solidify your approach.

Is there a way we can correct the work history, my employer suggested writing a letter to USCIS with new info, will that work ?

Who is your future employer? You need to write a correction via a claimant statement.

Can the new company do a H1B transfer for me before company B files for an amendment petition?

Yours is a good question and best served by contacting a competent attorney in your area for further evaluation and advice.

How much chances I have to re-enter ?

An attorney can certainly help to evaluate whether you have a viable claim and work with you to obtain documentation in support of your claim.

Contract - I do not understand certain terms in agreement

Call a local attorney who will read the entire agreement. This forum is just meant to be a system for getting quick answers.

Are we obligated to pay rent to the daughter in law who does not appear to own this home?

Yours is a good question and best served by contacting a competent attorney in your area for further evaluation and advice. Please upload some...

Was it the right choice to accept reunification in order to get a mental health evaluation of the father?

Yours is a good question and best served by contacting a competent attorney in your area for further evaluation and advice.