Instafold, followed by a pat on the back for making an emotionally hard fold, and doing it well - I have a very simple math reason:
The chance of any card
not being a diamond is 75%. There are four cards in your two opponent's hands. Therefore, the probability of none of those cards being a diamond is 0.75 * 0.75 * 0.75 * 0.75 = 0.3164. That means 31.64% of the time you're NOT facing a flush draw. Many live game opponents love their suited aces. A5d would be the second nuts here, and it is a very reasonable calling hand if you believe that there will be several callers behind you. A2s is also a possible holding for one of your opponents. KQs is a pretty reasonable calling hand for UTG+2, a looser, deep stacked player might also open with it from early position. I think you need to include QJs, and JTs as reasonable potential holdings for your opponent at UTG+2. Would you open UTG with QJs? hmm - tough, but you have described dude as very active, so possible.
At a more "advanced" table, with a deep stack low-suited connectors from early position can also make a great calling hand, if you think there will be a string of callers behind you now and then, because if you can get there, you will blow your table mates minds and they will fear you on basically every flop. But, that's not a play I recommend unless you're playing against a lot of good players who do good hand-ranging and you're able to hit the flop cheaply. That's a meta game approach that probably isn't necessary at 1/2. But you can't discount that from the range of UTG+2 - he would be doing this to meta-game the other grinder at the table that you haven't mentioned.
Given the board texture, I think the probability is that you're facing two flush draws, a made middling flush and a draw to a K or A flush, or possibly a straight draw and a flush draw, which means you need your full house to prevail, which requires the board to pair. You've got 7 outs (one 6, three 4s, three 3s) which gives you about a 15% of hitting it on the turn, and if you miss the turn about a 15% chance of hitting it on the river. You're facing a $34 pot that will cost you $8 to see that's 4.25:1, or about 25%. Calling here is negative EV.
If you're calling, you're calling because you believe one of your opponents is going to bet hard if you get there. The straight draw isn't going to bet hard into a flush - he might call if there are only three diamonds there, but I don't see the straight calling 4 diamonds. A typical value bet for someone holding a decent flush is going to be around 25-50% of pot. Given the calls, if someone has flopped a middling flush, or JT or QJ, they're probably going to be less excited about going for value at the river because of the two opponents who call the flush board. So, assuming you make your full house, if that diamond doesn't come on the turn or the river, the optimal situation for you is that the middling flush value bets into a $42 pot. On the other hand, if the diamond does come, the best situation would be UTG betting his king-high flush into UTG+1's ace-high flush, who reraises the paired board that you re-raise on... Your friend in the hoody isn't calling your reraise on a paired board and UTG one isn't calling your reraise - he will assume one of you have the A.
In my mind this kind of mid-strength hands is what makes you either a profitable player or a losing player - this is where the game of poker is - being able to assess if the bluff-catch risk is worth the reward of the call.
If the flop was something like 6d, 4d, 3c, I think it's a re-raise to say ~$24