In terms of adoption, mum has no options without dad's consent.
The court is charged with upholding people's rights and when it comes to the Family Law Act 1975, only children have rights, not their parents. A child has a right to know, be cared for, spend time and communicate with their parents on a regular basis. The circumstances around the child's conception, or the relationship between their parents, past or present, or the existence of an intervention order, or the fact that dad said he was 'using' the child, are immaterial against this right.
If the court were to order an adoption because mum doesn't want the child, even though dad does, it would be infringing on the child's rights, which are the only rights that matter to the court.
If mum doesn't want the child, perhaps she could consider consent orders that allocate sole parental responsibility to dad, but she will still have to pay child support, just the same as dad would if he decided he didn't want the child and mum did.