The book "Bahubivah" was written by Ishwar Chandra Vidyasagar, thus making option 2 the correct answer. Let`s look at why the other options are incorrect:

1. Raja Rammohan Roy was a prominent social reformer who had remarkable influence on modern Indian society. Although he did write many significant pieces, "Bahubivah" was not one of them.

3. Pandita Rambai was a social reformer and one of the pioneers in the field of women`s education in India. While she wrote and translated several books, "Bahubivah" wasn`t one of them.

4. Rabindranath Tagore was a Nobel laureate and a multifaceted artist, known for his poems, stories, and songs. He did write numerous works, however, "Bahubivah" wasn`t one of those.

"Bahubivah" was, in fact, written by Ishwar Chandra Vidyasagar who was a key figure of Bengal Renaissance. He was a philosopher, philanthropist, and a staunch campaigner for women`s rights including widow remarriage in India.