Ambani is a surname found in Gujarati people of India.
Ambani family grassroots are from Jasdan, a town near Rajkot, their Kul Devi (ancesestor godess), Phoolbai Maa is worshiped.
Ambani is also a surname in the Luhya tribe of Kenya's western province. The origin of the name is not clear but it is probably a translation of "Harambee" which was a call to unite or come together. "Hambani" in the Maragoli dialect means "unite" or "come together."
Some people of Ambani surname
References
Ambani Wikipedia(Text) CC BY-SA