All perfect praise be to Allaah, The Lord of the worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.
There are some issues that we need to clarify their rulings:
First: your wife authorized you to hurl the Jamaraat on her behalf. If she had an excuse, such as undergoing a severe difficulty by hurling the Jamaraat or fearing harm for her baby, it would be permissible for her to authorize you to hurl on her behalf. She would not be required to come with you to the place of hurling the Jamaraat. It is permissible to hurl the Jamaraat on her behalf while she stays at home in Mina or Makkah. If she did not have an excuse and there was no difficulty for her to hurl the Jamaraat, authorizing you to do it on her behalf would not be permissible. Additionally, she would be required to slaughter an animal for ignoring hurling the Jamaraat. Ibn ‘Abbaas said: “The pilgrim who ignores or forgets a ritual of his Hajj should slaughter an animal.”
Second: your wife did not spend the night in Mina. If she did not have an excuse, i.e. she could spend the second night like the first one, she would be required to give away one Mudd of food (according to Ash-Shaafi‘i) or slaughter an animal (according to Maalik). We adopt Imaam Ash-Shaafi‘i's opinion in this concern. One Mudd is approximately equal to 750 gm. However, if she had an excuse, like the pregnancy which resembles sickness, and could not spend the second night in Mina, she would not incur any sort of compensation according to the majority of scholars. The Prophet, sallallaahu ‘alayhi wa sallam, allowed the shepherds to spend the night outside Mina as well as the sick pilgrim by analogy due to the excuse both involve. Some scholars contested this analogy saying that the shepherds were given permission not to spend the night in Mina due to the public interest. Unlike the sick pilgrim; he does not spend the night in Mina for his own interest. However, the first opinion is stronger and analogy is correct.
Therefore, if your wife had an excuse, there would be nothing due on her. Yet, it is safer for her to give a way one Mudd of food, which is an affordable matter, in order to keep away from the divergence of scholars who banned the validity of the aforementioned analogy.
Spending the night on the third day of Tashreeq was not required of your wife because the sun did not set while she was in Mina on the second day of Tashreeq. So, her departure within two days was correct.
Allaah Knows best.