Water, water everywhere and all the boards did rot.

I had already planned on replacing some of the subfloor boards, just based on a cursory glance from under the house...they were nasty. But confirmation came when Grandma fell through the floor while cleaning.
Might as well make a project out of it. I removed three subfloor boards and the area where the floor decided to cave in. While I was at it I sistered in a joist next to a questionable one, you can probably see it on left side in this shot. I also secured another joist that was only sitting on about an inch of the cement support.
I also grinded out the old waste arm from the sink which was made of some soft metal, not sure what alloy, but the vent is cast iron.
And new boards for the subfloor in their place: