A black is a place that matter could get in and can never get out while a white hole is said to be a place where matter gets out and can never return, so basing on these descriptions it is impossible for these two to combine especially if the force exerted by both is equal because if one tries to attract, the other is repelling, and if we will say that white hole has greater energy it will be pushing black hole away and if a black hole has greater energy it will suck the white hole.