I wrote an if/elseif-statement but it only gives me the first condition answer, why?

also I had an eror (Unreachable code) the reason of the program is to give the prular of an english world and I didn't finished it yet --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- this is my code please help me

#include <stdio.h>
#include <string.h>
#include <stdlib.h>

int main(void)
{
  char word[100];
  int len;


  printf("plz enter a word : ");
  fflush(stdin);
  gets(word);
  len=strlen(word);
  char nword[100]={(char)malloc(len+3)};
  if(word[len-1]=='s'||'S')
  {
      strcpy(nword,word);
      nword[len]='e';
      nword[len+1]='s';
      nword[len+2]='\0';
      printf("the plural of your word is (%s)\n",nword);
      free(nword);

  }
  if(word[len-1]=='s'||'S')
  {
      strcpy(nword,word);
      nword[len]='e';
      nword[len+1]='s';
      nword[len+2]='\0';
      printf("the plural of your word is (%s)\n",nword);
      free(nword);
  }
  else if(word[len-1]=='x'||'X')
  {
      strcpy(nword,word);
      nword[len]='e';
      nword[len+1]='s';
      nword[len+2]='\0';
      printf("the plural of your word is (%s)\n",nword);
      free(nword);
  }
  else if(word[len-1]=='z'||'Z')
  {
      strcpy(nword,word);
      nword[len]='e';
      nword[len+1]='s';
      nword[len+2]='\0';
      printf("the plural of your word is (%s)\n",nword);
      free(nword);
  }
  else if(word[len-2]=='c'||'C'&&word[len-1]=='h'||'H')
  {
      strcpy(nword,word);
      nword[len]='e';
      nword[len+1]='s';
      nword[len+2]='\0';
      printf("the plural of your word is (%s)\n",nword);
      free(nword);
  }
  else if(word[len-2]=='s'||'S'&&word[len-1]=='h'||'H')
  {
      strcpy(nword,word);
      nword[len]='e';
      nword[len+1]='s';
      nword[len+2]='\0';
      printf("the plural of your word is (%s)\n",nword);
      free(nword);
  }
  else printf("ddd");

  return 0;
}