Woman posting pictures of herself on social media platforms

Q: Is it allowed for a married Muslim woman to wear makeup and post her pictures on social media platforms like imo, WhatsApp, Facebook and telegram without the consent of her husband? If not what is the Islamic ruling for a wife who constantly do such things by violating the command of her husband despite telling her several times to refrain from posting her photo on social media?

Please I need your advice on this matter. What should I do? I have been telling my wife several times not to post her photo as it is against the sharia of Islam, however after I convinced her, she takes my advice for time being and agrees not to do it again, but after some time she continued to do it again and again.

Waking up with some blood in one's mouth while fasting

Q: In Ramadhaan, when I wake up in the morning after sehri and performing fajar (for example 10 am). I always have a blood and it's taste in my mouth and I'm sure that it must have entered in my throat. What should I do for this because this is something impossible for me to control. And if this breaks fast then it means I have to repeat all my fasts. This problem is continuous with me. I cannot even make up previous fasts.

Giving zakaat to one's niece on her wedding

Q: If anybody wants to give zakaat to their sister's daughter on her marriage. They have a house and their way of life is normal. But in the age of today, a marriage arrangements is a burden on them.

In this matter, can we give zakaat to them without telling them that this is zakat so they can buy some things. In this case some other people also help them, somebody gave a bedset, someone gave other things. What does Islam say about this. 

Is ambergris pure?

Q: I would like to know if ambergris is pure. I've heard that it is either the vomit or faeces of a sperm whale. In light of the Shafi and Hanafi madhab, would a perfume containing ambergris be ritually impure?