These four terms are not all exact synonyms, so the term that is most suitable for your context will depend on the remedy that the law in question aims at. Here are the respective definitions:

Guardianship or conservatorship: a legal process, utilized when a person can no longer make or communicate safe or sound decisions about his/her person and/or property or has become susceptible to fraud or undue influence.

https://www.guardianship.org/what-is-guardianship/

Receivership: A receivership is a proceeding by which a state or federal court appoints a disinterested third person to take possession of certain assets, or in some cases assume control of the operations of a business. Receivers are also appointed to aid in the enforcement of judgments that have already been entered.

Sequestration: a special remedy by which a court can order a judicial officer (for example, a sheriff or, in federal court, a marshal) to seize property that is at risk of loss, often before the entry of a judgment.

Both of these definitions are found in this page:

https://www.uwlaw.com/practice-areas/bankruptcy-and-creditor...

In view of the multiple possibilites and the fact that the possibilities are not exact synonyms, it is incumbent upon you to find out exactly what the text is referring to.

One more point: In English, you need not use the word "law" in this context. You can simply say:

وبعدم خضوع ايا منهم لقانون الحراسة
And that neither one of them is subject to [guardianship, sequestration, etc.]

You don't say "under sequestration law" or "guardianship law."