Combining code for multiple sensors in a single program
In general:

All #defines and #includes get put from all separate sketches, at the top.

Globals and function definitions (except for setup() and loop()) get mixed together below the #defines and #includes.

All code in the separate setup()s get put in the combined setup().

All code in the separate loop()s get put in the combined loop().

You have to be aware that any loop() from the separate programs that include a delay() will likely have to be refactored to use the same kind of scheduled execution method as the Blink Without Delay example from Arduino. delay() stops the whole program while it twiddles thumbs, which means your other sensors aren't being read or managed during that time.