I also suggest staying mum for the time being, until she has all of the facts and options. I
n the interim, I'd suggest researching the State and Federal laws. I find it difficult to believe any employer would fire someone for being ill. As far as the pregnant former employee, depending on the type of work done by you daughter in law's company, there has to be more to the story, as Federal Law as well as most State's laws prohibit such a firing.
There are many, many, many Federally funded programs that your Son should look into, in the event your Daughter-in-Law does lose her job and/or benefits.
Please let us know how things turn out.