She became Muslim in secret and feared that her family might harm her, so she broke the fast one day in Ramadan; does she have to make it up?
Question

I embraced Islam recently without my parents’ knowledge. If they knew they would be very angry and would cut off my study allowance for university. Hence I tried to keep the matter secret. But on the third day of Ramadan, I had no choice but to go to a meeting at the University, and after I arrived I found out that they had prepared dinner that happened to be one and a half hours before Maghrib. The problem was not my refusing to eat with them; rather the problem was that my parents were also present at this meeting without me having any prior knowledge of that. I thought about the matter very carefully and I was afraid that they would find out about me being Muslim, especially since they had noticed my recent interest in Islam and my refusal to eat with them on the three previous days. If they noticed that I would not eat with them on this night, then they would undoubtedly find out that I had embraced Islam, and if that happened, the consequences would be dire. Hence I decided to break the fast on that day. I broke the fast and I asked Allah to forgive Me and pardon me.
My question is: do I have to make up this day or offer expiation?.
Praise be to Allah.We ask Allah, may He be exalted, to reward you immensely and to bestow His blessings, both apparent and hidden, abundantly upon you and to grant you beneficial knowledge and righteous deeds. We congratulate you for the blessing of Islam that Allah has bestowed upon you and for your love for Islam and for following its teachings in the manner prescribed by Allah. 
So long as you are afraid of severe consequences for showing your Islam openly, you are not obliged to show it openly in front of your parents. Allah will accept a person’s Islam even if he does not show it openly when he is not able to do so. So long as a person has entered Islam by uttering the twin declaration of faith (Shahaadatayn), he has to adhere to its teachings as much as he is able to after that, without causing any trouble for himself that may prevent him from continuing to follow this religion. Allah tells us that the believer from the family of Pharaoh concealed his faith from Pharaoh and his people, as Allah, may He be exalted, says (interpretation of the meaning): “And a believing man of Fira‘un’s (Pharaoh’s) family, who hid his faith said…” [Ghaafir 40:28]. Some of the Sahaabah (Prophet’s Companions) became Muslim in the early days, when the Muslims were in a weak position in Makkah, and the Prophet (blessings and peace of Allah be upon him) encouraged them to conceal their Islam for fear of trouble. One of these people was the great Sahaabi Abu Dharr al-Ghifaari (may Allah be pleased with him). The Prophet (blessings and peace of Allah be upon him) said: “O Abu Dharr, conceal this matter and go back to your own land, then when you hear that we have begun to prevail, come (and join us).”
Narrated by al-Bukhaari, 3328 
As you broke the fast on that day because of your parents’ presence, as you mention, and your fear of dire consequences if you did not break the fast, then you are excused for breaking the fast. But you have to make up that day whenever you are able to do so and are confident that no harm will befall you as a result. And you do not have to offer expiation for that day. 
We ask Allah to enable you to do that which pleases Him. 
For more information please see the answer to question no. 165426 
And Allah knows best.