transposition-with-key.php

<?php
$data = [
    'name' => ['a', 'b', 'c'],
    'email' => ['a@bc.de', 'x@yz.de', 'barde@bar.de'],
];

$output = [];
for($i = 0; $i < count($data['name']); $i++) {
    $output[] = array_combine(array_keys($data), array_column($data, $i));
}