She saw blood after she had done ghusl following menses and had intercourse with her husband. What should they do?
Question

                A man copulated his wife after she made ghusl following menstruation. On the same day and before she made ghusl of janaba (impurity after intercourse) she found blood. It is very rare for her to have longer period than normal. Did he copulate her while she is still menstruating?  If so, then how should they expiate? Should the wife make ghusl to clear the impurity of intercourse, or can she wait till the end of the day so that she can make ghusl to clear the impurity of both intercourse and menstruation? Are they sinful? Bear in mind that she was sure that her period stopped, she made ghusl and prayed.
Praise be to Allah.
    If she was certain that she had seen the tuhr (sign of purity 
    i.e., that the menses had ended), either complete dryness or the white 
    discharge by which women know that the end of the menses has come, then any 
    blood that appears after that is not regarded as menses, so it does not mean 
    that she cannot pray, fast and have intercourse. 

    But if you were not certain about the tuhr, rather you based 
    it on the usual end of your menses, then the blood was menses, because the 
    period may be longer or shorter than usual. 

    Shaykh Ibn Jibreen (may Allaah preserve him) was asked: 

    What is the ruling on the blood that appears on days other 
    than the monthly period? My period is usually nine days but in some months I 
    bleed on days other than the days of my period, but it is a very small 
    amount of blood, and it may last for a day or two. Do I have to pray and 
    fast during that, or make them up? 

    He replied: This blood that is extra to the period is 
    bleeding from a vein and is not counted as part of the period. The woman who 
    knows the nature of her period should, during the time of her usual period, 
    not pray, fast, touch the Mus-haf or let her husband have intercourse with 
    her in the vagina. When she becomes pure and her period is over, she should 
    do ghusl, then she comes under the same ruling as women who are pure (not 
    menstruating). If she sees a little blood or yellowish or brownish 
    discharge, that is istihaadah (non-menstrual bleeding) and it does not mean 
    that she cannot pray and so on. End quote. 

    Fataawa al-Mar’ah al-Muslimah 
    (1/277). 

    With regard to what took place of intercourse, there is no 
    sin on you for that, because you thought that the period had ended. 

    There is no sin on the woman if she delays ghusl for janaabah 
    so that she can do ghusl for menses and janaabah together, although it is 
    better for her to do ghusl for janaabah, because by doing so it becomes 
    permissible for her to read Qur’aan, as the one who is in a state of 
    janaabah is not allowed to read Qur’aan, whereas the menstruating woman may 
    read Qur’aan. 

    This has been explained in the answer to question no.
    2564. 

    And Allaah knows best.