If not, I would still recommend going ahead with a professional cleaning company that has experience with mold remediation (make sure they send before and after pictures as well), if you really wanted you could give a small credit to the tenant to make them happy as well but 100% not required. 

Once we were aware of this and the owner refused to properly remedy the issue we had to cut the property, we actually cut the client and his 6 other listings.

We were told we have mold in our basement and got 1 quote for mold remediation and it came back at $5,500.

@David Kirkpatrick hmmm... here are the problems I see with this scenario (and that you need to remedy).

The owner has 30 days to remedy the situation.

I had a remediation contractor come out, and he told me the levels on the report is what he'd expect from a basement in Portland, and any amount of washing / bleaching wouldn't reduce the levels much long term as more moisture would enter the space up from the slab because concrete will always give off some moisture, and he couldn't really recommend much remediation. 

Most of those deals fell out, but we were able to get price reductions/remedies for others based on the findings.

This is really disappointing because I am ready to purchase another property today but will not get approved or have horrible loan terms due to a 640 credit score.Does anyone have any recommendations on how to remediate this issue?

So, if your bathroom was un-permitted you may be required to remedy that issue with this renovation.

Landlord shall have the same remedies for the collection of such costs as Landlord has for the non-payment of rent under this Lease.