Can the non-custodial can use domestic violence and dcf involovment (mandated by law if any dv reported to police)as to say that a parent was unfit. Even is she and her family are the victims and she pressed charges/protection order. DCF cases where closed sayn the mother isn't at fault and no evidence that she knowly stayed in the situtation. However can the ex still try say she unfit for the safety of the child?

Yes, it can be used. It would be up to the court to determine the impact of the evidence towards proving unfitness.

If the charges were ruled unfounded, the NCP is going to look pretty silly bringing them up.