Get Category and Excerpt From wp_get_recent_posts

I would suggest using WP_Query() instead. Like so:

<?php
$category = 'whatever';
$new_query = new WP_Query(
    array(
        'post_type'         => 'post',
        'posts_per_page'    => -1,
        'category_name'     => $category;
    )
);

if ($new_query->have_posts()) {
    $i = 0;
    while ($new_query->have_posts()) {
        $new_query->the_post();
        $postid = get_the_ID();
        // Your output code.
    }
}
wp_reset_postdata();
?>

Merely change $category to whatever you need. Make it an array() if you want to have several categories.
If however, you will be doing this for a custom post type, you need to use the tax_query array, like so:

'tax_query' => array(
    array(
        'taxonomy' => 'people',
        'field'    => 'slug',
        'terms'    => 'bob',
    ),
),

Above example is taken straight from the WordPress Codex.