Yomi did accept the challenge, however Madara has ever since been trying to find IC leads as to the whereabouts of the Jinchuriki, so a battle itself never commenced.
Did you two talk about how the RP was to commence? Is that what you two agreed on? If so then, well, ok, that would count as an ongoing challenge and I'd have to wonder who went inactive first while the challenge was fresh. I likely wonder in vain since, considering the timeframe, that question is probably unanswerable (Konoha board only goes back ~ 178 days, and that's with it being inactive!).
At the time of the challenge, there were IC hunt biju rules in place. I and Sabu, I think, were the first to attempt to try to do an IC hunt following those rules (the setup phase did not end decisively, thread here:
https://forum.shinobilegends.com/index.php/topic,9477.0.html ) and from that experience I can empathize with you two not wanting to go through the
literal execution of the IC hunt as laid out in the rules.
Still, the spirit of the IC hunt rules was for you guys to at least have a discussion about making a confrontation/contest possible.
Anyways, with what info is on hand and presented so far, it can be claimed that, at least as of recent, Yomi went inactive during the challenge, and so Madara would get the beast, and would have to honor Hazama's challenge (assuming he's still challenging).