Can we file a lien on property foreclosed and now owned by Fannie Mae?

You missed your opportunity. Your beef was with the prior owner, not the new one. Had you placed a lien before the foreclosure you could have possibly regained some of your loss. However, if it is a mechanic's lien, you may still be able to go to the property and remove whatever you installed. Very few states allow this, though.

Certainly you can. When the lender foreclosed, they assumed full responsibility for any past due taxes or HOA fees, and all future assessments until they sell it, just like any other owner would. Foreclosure is in effect the same as if someone had bought that house; only the ownership changes. If they buyer does not check for and require that all be paid before closing, it becomes their obligation as the new owner.

So go ahead. FNMA will pay that (they might question it and require a boatload of documentation to prove the obligation) or they won't be able to pass clear title to whoever they end up selling to.

Probably to late. The person that owes the HOA dues no longer owns the property. Fannie mae does not owe that debt so why would they pay?!

Too late for that. You should have filed it before the foreclosure took place.

Now you will need to sue.

may as well have fannie mae keep it current yes

You are too late to lien it. The homeowner no longer owns the house.

It's too late for that.

Look at my fanny

Who is "we"?