Tsunade and Chiyo. Let's review the facts here - we have Kakuzu, who's strategically competent and could potentially cause harm to them, but we also have Hidan who, other than his immortality, is an utter, total dumbass. On the other hand, we have Tsunade who's a Kage level shinobi with years of experience behind her and an amazing physical strength. I could argue that with her Byakugo seal released and "One Hundred Healings" technique activated, she could solo them (though not without difficulty) but with Chiyo on her side, a combat veteran with excellent reflexes and several puppets under her command (which would be able to counteract Kakuzu's hearts), I don't even think she needs it.
1. Kakuzu's battle experience is higher the both of theirs (not combined)
2. The battled a tailed beast so Tsunade's raw strength isn't going to be impossible to handle
3. If Hidan gets Tsunade's blood it will be a problem, she may be able to regenerate but if he continues to stab himself in the leg or something she will be unable to move because she'll need to regenerate after each stab and Soon she will run out of chakra.
Now you may say chio could help her but all Kakuzu will need to do is that massive fire thing he did and her puppets are toast. I will not deni Hidan is a fool and Tsunade is good in a brawl but Hidan keep up with Kakashi so he ain't no slouch in close combat. Chio would need to have one off her puppets to decapitate him because Tsunade can't do much to him unless she uses that hundred seal thing. Even if she uses that seal Kakuzu could easily keep her at bay with long range ninjutsu but it will be difficult I won't deni that.
I will give this to Hidan and Kakuzu Mid difficulty to High at most.
@LordGriffin1000 Tsunade was stabbed by Madara's bigass Susano'o sword, broke that sword with mere strength, pushed it through her body and counter-attacked Madara. I think she can shrug off Hidan's table pool stick with relative ease. Kakuzu would be the only opposition and even he would give in eventually, with enough pressure.