If you don't need to use awk, paste could work:
$ cat fileB | paste -d $'\n' fileA - - - | tr -s $'\n' >fileC
user9549915
- 151
- 4
If you don't need to use awk, paste could work:
$ cat fileB | paste -d $'\n' fileA - - - | tr -s $'\n' >fileC