Both 1 and 2 are "true". It returns the call instruction, whose "value", when we execute the code, will be the return value of the function.

To illustrate, take this little Pascal program:

program p;

function f: integer;
begin
   f := 42;
end; { f }

begin
   writeln(f);
end.

Which translates to this LLVM-IR:

; ModuleID = 'TheModule'
target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"

%text = type { i32, i8*, i32, i32 }

@input = global %text zeroinitializer, align 8
@output = global %text zeroinitializer, align 8
@UnitIniList = constant [1 x i8*] zeroinitializer

define i32 @P.f() #0 {
entry:
  %f = alloca i32, align 4
  store i32 42, i32* %f
  %0 = load i32, i32* %f
  ret i32 %0
}

define void @__PascalMain() #0 {
entry:
  %calltmp = call i32 @P.f()
  call void @__write_int(%text* @output, i32 %calltmp, i32 0)
  call void @__write_nl(%text* @output)
  ret void
}

declare void @__write_int(%text*, i32, i32)

declare void @__write_nl(%text*)

attributes #0 = { "no-frame-pointer-elim"="true" }

The call i32 @P.f() is generated by:

inst = builder.CreateCall(calleF, argsV, "calltmp");

The contents of inst is %calltmp = call i32 @P.f() - and that is a CallInst 'value'.

and inst is returned to the evaluation of the expression for the argument to writeln.

CallInst::Create needs ArrayRef < Value* > for arguments

so now when you initialized ArrayRef < Value * > arguments('c'), here as there is no inbuilt constructor to convert char 'c' to Value*

you can do

ArrayRef< Value* > arguments(ConstantInt::get(Type::getInt8Ty(llvmContext), 'c'));

or you can directly pass single i8 type integer to CallInst::Create call

Instruction *newInst = CallInst::Create(hook, ArrayRef< Value* >{ConstantInt::get(Type::getInt8Ty(llvmContext), 'c')}, "");

see http://llvm.org/docs/doxygen/html/classllvm_1_1CallInst.html and http://llvm.org/docs/doxygen/html/classllvm_1_1ArrayRef.html#details for more details.