Two companies, one owned 100% by a husband and one onwed 100% by his wife. Both companies have employees. The companies are not related (other than the husband/wife ownership). Is this considered a controlled group??

Yes or no. Answer determined by constructive ownership of stock rules. Take a look at IRC 1563(e)(5) for corporations (as incorporated by 414(b)) and IRS Reg 1.414©-4(b)(5) for other trades or business.

Also watch out if it is a community property state. According to some experts (including my personal favorite, S. Derrin Watson) in a community property state, there is direct ownership and the "spousal noninvolvement" clause cannot apply.

This issue has been discussed here before, but you should also be aware of
1563(e)(6) which provides that the ownership of a parent is attributable to a minor child. Your post doesn't say whether the clients have any minor children, but, if they do, there may be a controlled group through attribution of the mother's ownership and father's ownership to the child.

Prior "spritited debate" addressing similar issues.