Originally posted by: Chandraketu
Vasudev was never king - in fact, Ugrasena diedafter the Yadava fracticide the same time that Vasudev did. After Arjuna arrived at Dwaraka to evacuate the survivors, Vasudev entrusted them all to his care, and passed away that night. Same happened to Ugrasena. (According to another account of the Puranas that I read but don't give much credence to, all the womenfolk, along with Ugrasena & Vasudeva commited self immolation). It's true that Ugrasena had no sons aside from Kamsa, but once Arjuna took everyone away, the only survivor from the family was Anirudha/Usha's son Vajra. Arjun installed him on the throne at Mathura, and left Subhadra with him as caretaker.
The one case of maternal succession I know of was Chitrangada. Since her father had no sons, he allowed Arjun to marry his daughter only on condition that her son would be an inheritor tohis kingdom, and not the Pandavas'. Since Babruvahana wouldn't have stood to succeed Yudhisthir anyway (although I wonder whether Yudhisthir wished that once the war was over?), Arjun had no problem accepting the request. Another by-product of this decision that Babruvahana was the only surviving son of Arjun after the war.