What do you mean "No"? How ? Why ?
Doesn't the MC deserves to have his sister back? Doesn't Melissa deserves to find her way "Home"? Why are you punishing her even more? What did she ever did to you? Uh? Uh? You... meanie... let the siblings find each other...
Not happy with you right now HP... Not happy...
Peace
Nothing is impossible, but again... as HornyyPussy said, it looks like a fantasy, to survive after a crash, then after a long period of time appears on the doorstep as if nothing had happened, this looks like a drama and a cliché, and for this you need logic and makes sense... everyone died, only my sister survived? and no one, not the grandmother or any of the relatives, even knew? especially a medical investigation and lists of deaths could give reason that she is not among the dead or survivors.
P.s And also, after the crash, the whole family, as well as Mc and nana, may have been waiting in anticipation, hearing about the incident and waiting, perhaps even in the hospital for news or not... after all, there, too, it could have been known whether they survived or not. so it's not a fact. someday maybe and will be when MoonBox finds plans in the Mc family, but for now it looks fast and too exaggerated