Legal Question in Business Law in California

My answer is a cautious "no" to the right of the laid-off person to priority in rehiring or recall. Such priorities are common under collective-bargaining agreements and in industries with formal seniority systems. Also, the term "laid off" can have different meanings depending on the practices and customs in a business or industry.......it can be a polite euphemism for "fired," or in can mean a temporary furlough where the person has an expectation of being recalled when needed.

Also, employers have to be careful about dismissing even at-will employees (as most are) for a bad reason. It's often said you can fire an employee for a good reason, or for no reason at all, but not for a bad reason (such as retribution for whistle-blowing, union activities, illegal discrimination, etc.).

I have not heard of the three-month rule, but it's possible that the person mentioning it may have heard of such a rule in the context of some union or governmental seniority system.

In general, and subject to the limitations mentioned above, employers can discharge workers and hire replacements at any time.

No. Unless there is a union contract or company written policy requiring 'rehire' rights, the employer is free to do as they please.