Her
    parents are threatening to hit her if she covers her face
Question

                I am a moslam woman from XXX,I wear higab
    (cover my hear).
I belive that I have to cover my face but my mother and father think that
    higab is to cover my hear only I try my best to convince them but no use. my mother
    threaten me to hit if I ever mention it agin. I don't know what to do I am in bad need for
    any advice.
Praise be to Allah.Know that wearing hijaab is a duty for women, and it is not
    optional. Allaah says (interpretation of the meaning):
 and to draw their veils all over Juyubihinna (i.e., their
    bodies, faces, necks and bosoms, etc.) [al-Noor 24:31]
and:
 and do not display yourselves like that of the times of
    ignorance [al-Ahzaab 33:33]
Know that the complete hijaab which you are observing is something which
    is very good, so you should thank Allaah for it and ask Him to make you steadfast. Be
    steadfast and Allaah will strengthen your heart.
What your mother has told you about hijaab meaning to cover the hair only
    is not correct. A womans beauty is in her face, not only in her hair, and Allaah has
    commanded that her beauty should be covered, as He says (interpretation of the meaning):
 and not to reveal their adornment [beauty]
    [al-Noor 24:31]. The focal point of beauty is the face, so it must be covered,
    according to the most correct view among the scholars.
Know that Allaah is testing you by means of your mother, so see whether
    you will obey Him or her.
You have to advise your mother in a number of ways, including the
    following:
Speaking to her directly, or giving her a tape by one of the scholars
    which clearly outlines the ruling on hijaab, or giving her a book on this topic. Or you
    could call one of the shaykhs on the phone and ask your mother to listen to his answer; or
    take your mother to an Islamic lecture where the correct ruling on this issue will be
    discussed  or some other means.
If you are patient, keep hammering the point and pray to Allaah to open
    her heart at the times when duaas are answered, you will get results in sha
    Allaah. If your mother does not respond, then you do not have to obey her in this
    particular matter, because the Prophet 
 (peace and blessings of Allaah be upon him) said:
    Obedience is only in matters that are right and good. And there is no
    obedience to any created being if it involves disobedience to the Creator. At the same
    time, you have to be kind and respectful towards her, because Allaah says (interpretation
    of the meaning):
As for those who strive hard in Us (Our Cause), We will surely
    guide them to Our Paths (i.e., Allaahs Religion  Islamic Monotheism). And
    verily, Allaah is with the Muhsinoon (good doers). [alAnkaboot 29:69]
and:
O you who believe! Endure and be more patient (than your enemy),
    and guard your territory by stationing army units permanently at the places from which the
    enemy can attack you, and fear Allaah, so that you may be successful. [Aal
    Imraan 3:200].
And Allaah is the True Guide, there is no god besides Him.