typedef struct {
    char *a;
    char *b;
} row;

row* get_row(dbrow d) {
    row *r = malloc(sizeof(row));
    r->a = malloc(5);
    strcpy(r->a, d.a);
    r->b = malloc(5);
    strcpy(r->b, d.b);
    return r;
}

void get_rows(row **rows) {
    ...
    rows = malloc(rowNumber * sizeof(row*));
    int i;
    for (i = 0; i < rowNumber; i++) {
        rows[i] = get_row(dbrow);
    }
}

rows = malloc(rowNumber * sizeof(row*));

void get_rows(row ***rows) {
    if(!rows) {
        signal_some_error();
        return;
    }
    ...
    *rows = malloc(rowNumber * sizeof(row*));
    ...
}