May be try like this:
foreach( $post_ids->posts as $id):
// get the post title, and apply any filters which plugins may have added
// (get_the_title returns unfiltered value)
$name[] = apply_filters('the_title', get_the_title($id));
$lname[] = get_post_meta($id, 'last_name', TRUE);
$address[] = get_post_meta($id, 'address', TRUE);
$cinfo[] = get_post_meta($id, 'contact_info', TRUE);
endforeach;
$data = ['fname'=>$name, 'lname'=>$lname, 'address'=>$address, 'cinfo'=>$cinfo];
<script>
$( "#name" ).autocomplete({
source: <?php echo json_encode($data['fname']]); ?>
});
$( "#lname" ).autocomplete({
source: <?php echo json_encode($data['lname']]); ?>
});
$( "#address" ).autocomplete({
source: <?php echo json_encode($data['address']]); ?>
});
$( "#cinfo" ).autocomplete({
source: <?php echo json_encode($data['cinfo']]); ?>
});
</script>