Restore a WordPress database from .frm and .idb only
In general, if you're using MyISAM tables, you might be okay. See https://stackoverflow.com/a/879268/2385479 for instance.

If your tables are InnoDB, then it's a bit more difficult. According to https://serverfault.com/a/487534/67211, it seems the ibdata1 file is rather important.

Based on the error message, what I believe is happening here is that your database structure is being read correctly from the files you were able to recover, but the underlying table structure and associated data itself is in the missing file.

If it's a MyISAM table type, you can attempt to recover it (in phpMyAdmin click the Operations tab and look for the Repair text; from the command line or SQL tab just type REPAIR TABLE wp_commentmeta;.

Sorry for the bad news, but it doesn't look good.