"I have a map, if anybody's lost and need information."

or
"I have a map, if anybody's lost and needs information."
"I have a map, if anybody's lost and (if anybody) needs information."

The words 'if anybody' have been omitted because they are redundant to the meaning of the sentence. 'anybody' takes a singular verb, so it is 'if anybody is lost' and 'if anybody needs information'.