Function free() in C isn't working for me

Question

I have been trying to free memory allocated via malloc() using free().

Some of the structs it does free but leaves some the way they were a

Answer 1

Calling free does not set the pointer to NULL. You have to do that yourself.

7.21:  Why isn't a pointer null after calling free()?
    How unsafe is it to use (assign, compare) a pointer value after
    it's been freed?

A:  When you call free(), the memory pointed to by the passed
    pointer is freed, but the value of the pointer in the caller
    probably remains unchanged, because C's pass-by-value semantics
    mean that called functions never permanently change the values
    of their arguments.  (See also question 4.8.)

    A pointer value which has been freed is, strictly speaking,
    invalid, and *any* use of it, even if it is not dereferenced,
    can theoretically lead to trouble, though as a quality of
    implementation issue, most implementations will probably not go
    out of their way to generate exceptions for innocuous uses of
    invalid pointers.

    References: ISO Sec. 7.10.3; Rationale Sec. 3.2.2.3.