I have heard "Datta Bavani" many times. In this there are verse
"Kidho sajivan te nirdhar"
Means Lord Datta brought someone to life back after death. I would like to know, how many people were brought back to life by Lord Dattatreya?
As far as I know, Dattatreya himself has never brought anyone back from the dead. But the Gujarati song Datta Bhavani isn't limited to the deeds of Dattatreya; it also talks about Narasimha Saraswati, the fourteenth-century Swami whom some people believe was an incarnation of Dattatreya.
Here's what this translation says regarding the verse you're referring to:
Zalar Khai Rizyo Aem Didho Suvarnaghat Saprem Brahmanstreeno Mrut Bharthar Kidho Sajivan Te Nirdhar
Pleased with just Lima Beans (vhalore) meal, you lovingly bestowed upon the family a pot full of golden treasure. You undoubtedly restored to life the dead husband of a brahmin lady (in Gangapur)
This is a reference to a story involving Narasimha Saraswati, told in this chapter of the Guru Charitra, the traditional account of Narasimha Saraswati's life. A Brahmana widow takes her husband's body to Narasimha Saraswati and asks him to bring her husband back to life. Narasimha Saraswati does so by reducing his length of life in his next birth:
She was praying all the way in the mind. `Oh Trimurty, your fame is widespread, and you possess all siddhis. If a complaint is made to a ruler, he gives justice. If one goes to a physician, he gives medicine for relief. I camecrossing 20 villages with the hope that my husband will recover. I am coming to ask you how my husband expired on the way.
She saw Shri Guru sitting below an Ashwatha tree and she bowed to him respectfully. Shri Guru, blessed her and said, 'you shall have soubhagya for ever. She again bowed to Shri Guru and he exclaimed 'you will have 8 sons' The Brahmins accompanying her told Shri Guru, `her husband has expired and she has come here to see you before observing Sati.'
Hearing this Shri Guru smiled and said, `Her Soubhagya is everlasting. Bring her husband's body here immediately. Let me see when he lost his life.'
Some persons soon brought the dead body before Shri Guru. The strings were cut and the cloth covering was removed. the Tirth of rudrabhishek was sprinkled on the dead body and Shri Guru looked at it with his sight full of nectar. Immediately the Brahmin youth sat up as if aroused from sleep. He was ashamed to see himself without clothes. He wore the dhoti and asked his wife why she did not awake him before, why he was brought there and who was the Sanyasi. the wife narrated to him all that had occured. Then both of them bowed to Shri Guru with devotion and began praying to him. All the persons who had assembled there were delighted to see the miracle.
One cynic person said to Shri Guru. `This Brahmin died as per his fate. How can he be alive?'
Shri Guru smiled and said, `I requested Brahmadeo to give 30 years' life from his next life to this brahmin youth.'
I'm not a follower of Narasimha Saraswati or Shirdi Sai Baba (some of his followers believe he was a rebirth of Narasimha Saraswati), so I'm skeptical of this story.