To combat Mateus and her undead cronies, you may wish to bring in a White Mage with Full-Life, a Summoner with Phoenix, and any Hunter. Full-Life will instantly kill a Vampire, however, Phoenix is a better choice because of its wide area of effect and 100% accuracy. If your Summoner has not learned Phoenix from the Nirvana Staff, Madeen, Curaga and Unicorn are also good options. You should place a melee unit with a move range of 4 or higher (perhaps a Ninja) in the front row within reach of Mateus. On that unit's first turn, it can score a hit on the Totema while your mages blast the Vampires with Holy spells. Mateus should only get off one spell, most likely Thundaga or Star Cross, before the absence of minions makes her an easy target for a KO.