Guest complains about cleanliness - How should I respond?

[Melissa Bovee]

Ugh - not the morning I was hoping for! A guest sent a note last night (after I went to bed) that the toilet was not clean.  I was very responsive to her this morning (at 5am her time) and sent $75 through the platform.  Then after I sent the discount, she sent more complaints about bedding, stating, 
     "It was also brought to my attention the bedding had stains on stains in almost every bed and some of us decided to sleep on the floor. I’ve attached pictures for you to see.

She is right, there are some spots on the bedding - nothing that would have made me sleep on the floor for (especially since there were spare comforters for each bed in the closets), but still disappointing and fair feedback.  I have asked my cleaner to change out the duvet covers.  I realize that I need to get a process in place to make sure the comforter covers are getting cleaned on some frequency... 

My questions for you folks are: How do I respond to the guest now?  She is checking out right about now and was only a one night booking - so not much chance to make it right.  Do I refund her the night?  What should I say?  Should I have waited for her to check out to give her the $75?  Part of me wonders if the bedding stuff surfaced because she was looking for more refund $... (Either way I'm happy to have the feedback on the bedding so I can fix it going forward, just not sure if I handled this as well as I could have) .  Also, what is your cleaning protocol around comforters / duvet covers?  How often are they cleaned?

Thank you for the help and moral support here on this bummer host day! - Melissa