try this
$currencyFormat = '_($* #,##0.00_);_($* (#,##0.00);_($* "-"??_);_(@_)';
$textFormat='@';//'General','0.00','@'
$excel->getActiveSheet()->getStyle('B1')->getNumberFormat()->setFormatCode($currencyFormat);
$excel->getActiveSheet()->getStyle('C1')->getNumberFormat()->setFormatCode($textFormat);`