“For what purpose would she need to mention if she has a husband in this situation?”
It’s simple: she is telling us her story but if there was a second income, why then it would be a different story. And if there is no man in the life of a 5-month pregnant woman, that itself is a story worth telling, especially given the context which is the depiction of her difficult circumstances. Cue Jane Austen: it is important for young women and their parents to focus on what can go wrong when it comes to men and sex.
Sorry, but the 1950s are over. Employers are not entitled to know a woman's marital status and it is none of your business in this situation, either. We are no longer living in the era when employers get to discount a woman's eligibility for full benefits because she is married, or not.
Either she is a full employee with the same benefits as her male co-workers and the same respect as male veterans, or she is not. if the government is going to have been so hare-brained as to make women eligible for combat, they also have to support a woman's right to equal treatment regarding benefits.