This ... was not a great movie, but if we take it's twist at face value, then no, there was no way to prevent Emma's death.
The premise of the movie, is Alexander's quest to find the answer to question, which I am possibly paraphrasing: "Why can't you change the past?"
And the answer he finds at the end, again a paraphrase, is: "Since you invented time machine, to change the past. The past can't change, otherwise you would not have invented the machine to begin with"
It is not an original time travel paradox solution but, it is the one the movie goes with and for what's it worth, this aspect, is portrayed well. As is, it implies, that should you change the past, the past will correct itself in a way that prevents the paradox.
While yes, Alexander could have invented time machine for different reason, the logic of the paradox would remain and changes should therefore not remain.