What is the ruling on not fulfilling a vow?
A vow is a commitment towards Allah, The Almighty, and so, it should be observed as much as possible, and it is impermissible to take it lightly. Allah, The Exalted, Says –in commending the believers (What means): "(Because) they perform the vow and fear a day whereof the evil is wide-spreading." [Al-Insan/7].
Is the two Raka's after Friday Prayer an act of Sunna?
Performing Two prostrations after the call of Friday's Athan is an act of Sunna, since Al-Bukhari stated in his Sahih: (The chapter of praying before and after Friday's prayer). This indicates that he mentions Friday's prayer exactly as the Duhr prayer (Afternoon prayer) as regards praying before and after the call of Athan. And Allah Knows Best.
Is it permissible for a wife to give her money to her family as a charity, or a gift without asking her husband, or seeking his consent?
The wife has the right to give her money as a charity, or a gift to her family, or to other people after consulting her husband out of respect, and this is the meaning of treating on footing of kindness and equity. Therefore, if he wanted to stop her from helping her family, then there is no harm in not telling him.
Is it permissible for a Muslim woman to uncover her hair in the presence of a Christian woman?
All perfect praise be to Allah, the Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad, sallallahu ‘alayhi wa sallam, is His slave and Messenger.
According to the reliable opinion of the Shafie School of Thought, this isn`t permissible. However, some scholars stated that it is permissible for a woman to uncover what she usually uncovers while doing housework, but this differs from one place to another where some women uncover their hair while some don`t. However, this is provided that a woman doesn`t uncover her hair in the presence of non-Mahram men (Men permissible for a woman to marry). And Allah The Almighty Knows Best.