I've read the OP and many of the comment with incredulity. MOnica's response reassured me that not everyone sees Pakistani Muslims as dangerous.
Most people of Pakistani origin will try and visit their families in their homeland, even if they themselves were born in the UK. It's what people do, like Polish, Ukrainians, Italians, Greeks, French etc - people seek to see the country their family originated from.
The OP's daughter is in what she clearly sees as a life long relationship. In the absence of evidence that this man is abusive or plans to marry one of his daughter's off during the visit to Pakistan, it seems unnecessarily alarmist to take these views. It's also something that could increase any rift between grandmother, her daughter and grandchildren. These children, like most children, probably love their father very much and will be excited about visiting his family of origin.