these are files required to handle ADC and LCD. there will be one main program file in which the functions of these files are used.
you have to make one main program file in KEIL.
then in the same folder you have to copy-pest adc.c, adc.h, lcd.c and lcd.h all files.
in the main file include lcd.h and adc.h as
#include “adc.h”
#include “lcd.h”
see if this solves your problem