In the grand scheme of things, your university marks will be the majority consideration in your evaluation as a candidate.
University results are far more predictive of how well you do in a university environment than an ATAR score. They will use as many university results as you can provide. As you are in the end of your second year, your ATAR will be paid little (or perhaps even no) consideration. We can only speculate as we are not privy to the exact internal selection methods Monash uses.
If you are transferring to a single generalist degree (arts, science, etc), you will need about a 60-70 average of your marks. Double degrees will need 70-80 (depending on the degree). Law will likely need high 70s or 80s. Other degrees like education and more specialised degrees i really cant answer. In this case, you could always try emailing the university and asking, the worst that could happen is that they say no.
Either way, i'm sorry to hear your course hasn't been working for you, i hope your situation improves for the better :3