Assuming we take the film's official novelisation at its word, the answer is that the Strangers (whose race only numbered a few dozen) all died out at the end of the film, killed by the rotation of the world into the sunlight.
From the book's prologue
Which was sufficient. Until they chanced upon a small blue world
orbiting a minor star. The planet abounded in two elements that were
lethal to the Strangers. One was water. The other was sunlight.
Murdoch takes control of the machine
A straggling group of Strangers advanced warily, eyes fixed on Mr. Book’s floating corpse. Murdoch understood they were helpless now. The city was no longer theirs to control. Nor was he.
One by one the Strangers scurried back into the shadows like frightened silverfish. Within moments the streets were completely deserted. A ghost city.
And from the book's final page. Note that hiding in the shadows is insufficient to save Mr Hand
Suddenly sunlight beamed into the corridor as Murdoch stepped away from the door — driving Mr. Hand back like a panther fleeing fire.
Weakly, the Stranger stumbled back into the protective darkness. When he reached the stairs he saw the muddy lake bubbling up.
Trapped between water and sunlight, Mr. Hand crawled into the shadows and curled up to die . . .