The following are some informal comments about your question, but is not intended to be legal advice:
You did indicate why you are asking this question. The answer might depend on the context.
There is no state law of which I am aware restricting the number of occupents in a mobile home. It is possible that some local ordinance or zoning law could apply. The mobile home park might also have some regulations.
If your concern is about the welfare of the children, it depends on the circumstances. While this is certainly less than ideal, there is no hard and fast rule requiring a certain number of bedrooms. It is not uncommon for lower income families to live in smaller homes, and they often make do with what they can afford. This might require one or more of the adults to sleep on the living room couch, for example.
If this is an issue in a child custody case, the court would certainly consider it as one (of many) factors affecting the decision.