It is mandatory to use "return" and "void" in the functions? in C

Example:

void Function(int Number)
{
   process.....

   **return;**
}

It is mandatory to use "return" at the end of each function or not?

Example 2:

void Function(**void**)
{
   process...
}

The use of "void" is necessary if I need not receive any value?

Some say no and others say yes. What is right for a perfect understanding for the compiler and best practice in C ?.