These characters all go different directions.
Malcolm and Donaldbain, both fearing that they will be accused of Duncan's murder, "get out of Dodge" so to speak. Malcolm heads south to England where he seeks sanctuary with the English king. Donaldbain heads west to Ireland where he will find a safe place to stay until order is restored.
Ross and Macduff both stay in Scotland. Ross chooses to go to Scone to see Macbeth made the new king of Scotland. Macduff decides to go home to Fife. One would think that he should attend the ceremony at Scone since he is also a thane but for unspoken reasons, he tells Ross he is going home.
So for various reasons these four men go different directions.
Macduff; "Malcolm and Donaldbain, the King's two sons,
Are stol'n away and fled, which puts upon them
Suspicion of the deed".
These two, innocent, are accounted for. Malcolm goes into England, and enlists the help of the English king, Edward the Confessor, in raising an army to face Macbeth. Donaldbain to Ireland.
Ross: Will you go to Scone?" ( and witness the coronation of Macbeth as King of Scotland, 10th century)
Macduff: "No cousin, I'll to Fife".( And spend the meantime with my wife and family, soon to be murdered by Macbeth!).
Interesting that Shakespeare introduces an 'old man' to this scene, who uses an old ENGLISH word at the end of it, 'benison'. Derived from 'benefice' or kind words and good thoughts.