As per the Hindu Adoptions and Maintenance Act, 1956, a married woman can adopt a child

Section 8 of the Hindu Adoptions and Maintenance Act, 1956, as amended by the Personal Laws (Amendment) Act, 2010, lets any Hindu female of sound mind who is not a minor adopt, but if she has a husband living "she shall not adopt a son or daughter except with the consent of her husband". The consent is unnecessary only if the husband has finally renounced the world, ceased to be a Hindu or been declared of unsound mind. So a married woman can adopt, but with her husband's consent.