search "floating timber stairs" in HOUZZ photos and there's pages of examples...which one gets the vote??

Victorian Ash/Tassie Oak is worth looking at but possibly yellower than you are looking for. Blackbutt is another option. Both are suitable for flooring.

The black tread would be nice if you were having black flooring everywhere else. I think given you are having matte tallowood everywhere else, it is more streamlined and less 'bitsy' if you stayed all with the one surface.

Go for option C, possibly with a dark timber for contrast and drama. If it is slightly different it will look slightly off and annoy you forever. However I would be asking the question "why it is not available for stairs?". Stair treads get heavy use so you need a durable timber. If there is a question over the durability of Whian Whian Blackbutt for stair treads then maybe you should reconsider it for the rest of your floor? Best of luck, Dr Retro of Dr Retro House Calls