Wife period came late and its thick and brownish...late of 2 weeks....just gave birth 7 months ago?

Monitor : Irregular periods are one of the most common problems obgyns treat. If this is one time problem it usually resolves on its own. If this is a recurring problem you should be evaluated. Infections & hormonal changes can cause spotting. If there is a concern for pregnancy then do a home pregnancy test . There are many options available to help regulate the menstrual cycle. Schedule a visit.

Pregnancy test : I'd recommend she take a pregnancy test. It's possible for her to be pregnant even if she is breast feeding.