Translation:She's not there either.
mouth (>to ask) | where哪 ( na / nă ) Chinese example words containing the character 哪 ( na / nă )
哪里 ( năli = it is nothing ), 哪儿 ( năr = where )
there | those那 ( na / nà ) Chinese example words containing the character 那 ( na / nà ) 那边 ( nàbiān = there ), 哪个 ( nàge = that ), 那里 ( nàli = there ), 那么 ( nàme = so ), 那儿 ( nàr = there ), 那些 ( nàxiē = those ), 那样 ( nàyàng = like that ),
Both "She isn't here either" and "Neither is she here" should be acceptable, but "She isn't here neither" is definitely non-standard.
Personally, I would see that double negative as additional emphasis that she isn't in a particular location, like "You say that she's here, but I'm telling you she isn't!"