What is the best practice to delete intermediate pointers generated in nested function calls?

I am writing a basic matrix library in c, and the matrix data structure looks like this:

typedef struct Matrix{
    int rows;
    int cols;
    double complex *matrix;
} Matrix;

and the corresponding function to initialize the matrix and the function to free the pointer(similar to constructor and destructor in c++)

Matrix* InitializeMatrix(int r, int c){
    Matrix* mat = malloc(sizeof(Matrix));
    mat->rows = r;
    mat->cols = c;
    mat->matrix = (double complex *)malloc(r * c * sizeof(double complex));
    return mat;
}

int DeleteMatrix(Matrix *mat){
    mat->rows = 0;
    mat->cols = 0;
    free(mat->matrix);
    mat->matrix = 0;
    return 0;
}

Here is the main problem. Suppose I have two functions

Matrix* fun1(Matrix* input){
    //some operations
    Matrix* mat = InitializeMatrix(r, c);
    //some operations
    return mat;
}
Matrix* fun2(Matrix* input){
    //some operations
    Matrix* mat = InitializeMatrix(r, c);
    //some operations
    return mat;
}

Now I have another function want to nest fun1and fun2

Matrix* fun3(Matrix* input){
    return fun2(fun1(input));
}

Usually when I call a function, I will have to call DeleteMatrix to free the memory, but in fun2(fun1(input)), the reference to the matrix generated by fun1(input) is not saved, and cannot be freed. I know I can create a intermediate variable to make that reference, but I would like to keep nested function calls since it is neat and intuitive. Is there a problem in my overall design? How to overcome this problem?