It has to tick various boxes/meet a threshold. Murder (or attempted murder )is all to do with intent which is very hard to prove from a pushing situation. Did he intend to kill her. Because he had his back to the bus it would be very easy for him to argue he was unaware it was coming. He could even argue he didn’t intend for her to fall into the road.
I actually know someone who killed another person during a brief argument where the victim was pushed over. He was charged with both murder and manslaughter which I believe is unusual and went to crown court on both charges. The judge quite early on said the murder charges were not to be considered as it didn’t meet the threshold for murder. And this was a case where because the victim knew the perpetrator it could have been argued that there was possibly more chance for premeditation.
it is tricky because premeditation doesn’t have to be lengthy. But you do also need intent to kill and that’s very hard to prove. More so when the victim didn’t die.