Vaidyanatha Diksita's own name for his work is Smrti-Muktaphala-Nibhandana-Grantha. We know very little about the author of this extremely useful book. Diksita must have lived some two hundred years ago; he belonged to Kandiramanikkam, near Nacciyarkoil (in Tanjavur district). It must be noted that he himself practised the dharmas he had dealt with in his nibhandana and he is also believed to have performed big sacrifices.
Vaidyanatha-Diksitiyam is considered superior to similar works by Medhatithi, Vijnesvara, Hemadri and so on. Exhaustive in nature, it deals with the duties and rites pertaining to the different castes and asramas (the four stages of life), ritual purity, sradhha, prayascitta, stridharma, dayabhaga, dravyasuddhi. It even gives directions about the division of paternal property. When the Hindu code Bill was introduced in free India some put forward the view that the division of property must be based on the sastras. Such division is called "Dayabhaga". The division of property in Kerala, in the uncle-nephew line, is called marumakkatayam. The word "dayadi" is derived from "daya".
Diksitiyam is the last among the nibhandanas. In the preparation of this work Vaidyanatha Diksita had the advantage of making a comparative study of all the previous works on Dharmasastra. Before it the authority followed it to some extent in the South was the nibhandana of Tozhappar. Vaisnavas and Smartas alike today accept the Diksitiyam as an authority.
The nibhandanas are not like the Vedas (Sruti), the Kalpa-sutras and the Smrtis. Since they came later it is not easy to make them acceptable to all. Diksita, it must be noted, does not show the least trace of bias in his work and has followed the Mimamsa in determining the meaning of Vedic texts. He has brought together previous sastras and arrived at conclusions only after resolving the contradictions in them. This is the reason why his work is considered as authority in the South. When the Smrtis differ in some matters, he takes a broad view and suggests: "Let each individual follow the practices of his region and the tradition of his forefathers".
For a general background, please see here