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.
If the situation is as you described, then your in-laws have done a great evil and committed a hideous act. Forcing a Muslim to become a Kaafir (a disbeliever) is one of the gravest acts of injustice and corruption. In addition, breaking the marriage bond and causing separation between a man and his wife is grave injustice, and it is the work of Satan. You asked, "Is it acceptable for them to forcefully make her return to Hinduism without asking me?" We could not understand the intended meaning of this question. However, there is no doubt that compelling a Muslim into apostasy is unacceptable regardless of whether they asked you or not.
Your wife must escape from her parents' house and protect her religion to the best of her abilities. You have to free her from them and protect her from their evil to the best of your abilities. We advise you to consult with local scholars whom you trust to be righteous and knowledgeable to help you find a way to save your wife.
Finally, if your wife willingly left Islam without being forced, then it is not permissible for you to remain married to her; your marriage bond has been annulled by her apostasy, unless she reverts to Islam before the ‘Iddah (waiting period) expires. In this case, the marriage bond would still be intact. For more benefit, please refer to fatwa 87535.
Allah knows best.