I installed OOO a month after installing MMM. Reinstalling MMM resolved the CTDs.
Then I re-enabled all my mods and went to cell [2,0] and it froze again! So now I must start from the beginning and add a few mods at a time to figure out what is causing it.
So the MMM for OOO issue is resolved. The other issue is still open. At least it's a step forward!
[Reopened]

So wrong install order can cause CTDs. I thought it might cause graphical glitches rather. Good to know.

Back to square one.
I went back to the configuration below and loaded my save again:

Active Mod Files:		00  Oblivion.esm		01  Oscuro's_Oblivion_Overhaul.esm  [Version 1.34]		02  Mart's Monster Mod.esm  [Version 3.7b3p3]		03  Mart's Monster Mod for OOO.esm  [Version 0.9.9MB3]		04  Unofficial Oblivion Patch.esp  [Version 3.3.4]		05  Oscuro's_Oblivion_Overhaul.esp  [Version 1.34]		06  Mart's Monster Mod for OOO.esp  [Version 0.9.9MB3]		07  Encumbrance200.esp		08  Bashed Patch, 0.esp		

I started walking toward cell [2,0] then I heard the sound of the unknown creature and I returned to the point where the save was made and CTDd!
Here's the BSA in question: "Mart's Monster Mod for OOO.bsa"
Next I will remove MMM for OOO again, in order to properly isolate it from the test then post results.

I removed MMM for OOO and retested twice. No CTDs or sounds from the unknown creature.

Active Mod Files:		00  Oblivion.esm		01  Oscuro's_Oblivion_Overhaul.esm  [Version 1.34]		04  Unofficial Oblivion Patch.esp  [Version 3.3.4]		05  Oscuro's_Oblivion_Overhaul.esp  [Version 1.34]		07  Encumbrance200.esp		

Then I re-enabled MMM for OOO and retested:

Active Mod Files:		00  Oblivion.esm		01  Oscuro's_Oblivion_Overhaul.esm  [Version 1.34]		02  Mart's Monster Mod.esm  [Version 3.7b3p3]		03  Mart's Monster Mod for OOO.esm  [Version 0.9.9MB3]		04  Unofficial Oblivion Patch.esp  [Version 3.3.4]		05  Oscuro's_Oblivion_Overhaul.esp  [Version 1.34]		06  Mart's Monster Mod for OOO.esp  [Version 0.9.9MB3]		07  Encumbrance200.esp		08  Bashed Patch, 0.esp		

Loaded my save and heard the unknown creature and footsteps then CTDd as I was turning to see it.

Next I'm going to do a clean save and wait 4 days and save.
[Reopened]

I've done a lot of testing and I think the problem comes down to a nuked cell. So the question is how can I fix the cell?
Is there an Enhanced Editor for Oblivion, like the one for Morrowind?

Hmm, I was afraid that that might be the case. I lost a 400-hour character about a year ago to a nuked cell.
(And, to emphasize that this can be a Vanilla problem: my nuked cell occurred on the PS3, where no mods other than KoTN and SI are available.)

I'm afraid I know of no savestate editor that can fix such an issue. If anyone else does, I would be interested as well.

Ok, Then I will just have to avoid that cell. Thanks for letting me know!

I'm going to try some more testing after a long break.
I went back to an earlier save and jumped to the Testing Hall. This way if I remove all my house mods I will have a place to wait 4 days.
After arriving I did a save.
Then I removed all other mods accept UOP and OOO.

Active Mod Files:		00  Oblivion.esm		01  Oscuro's_Oblivion_Overhaul.esm  [Version 1.34]		02  Unofficial Oblivion Patch.esp  [Version 3.3.4]		03  Oscuro's_Oblivion_Overhaul.esp  [Version 1.34]		04  Encumbrance200.esp		05  Bashed Patch, 0.esp		

Then I loaded the save from the TH. Then I saved again.

Then I reinstalled MMM and enabled it along with UOP and OOO.

Active Mod Files:		00  Oblivion.esm		01  Oscuro's_Oblivion_Overhaul.esm  [Version 1.34]		02  Mart's Monster Mod.esm  [Version 3.7b3p3]		03  Mart's Monster Mod for OOO.esm  [Version 0.9.9MB3]		04  Unofficial Oblivion Patch.esp  [Version 3.3.4]		05  Oscuro's_Oblivion_Overhaul.esp  [Version 1.34]		06  Mart's Monster Mod for OOO.esp  [Version 0.9.9MB3]		07  Encumbrance200.esp		08  Bashed Patch, 0.esp		

Then I loaded the save from the TH and waited 4 days. Then I saved again. This will be my starting point for further testing.
I reloaded TH save and then did coe to [-1,-1] and walked toward cell [2,0]. No problem entering cell [2,0]. Retest a few times.
At this point, I will add more mods and retest until I fail to enter cell [2,0]. The hope is to find some conflict with the other 171 mods.

My question is, using the same TH save can I:
go back to WB, add more mods, rebuild the patch, load the save, coe to [-1,-1] and head toward cell [2,0] or should I:
go back to WB, add more mods, rebuild the patch, load the save, save again, reload the save, coe to [-1,-1] and head toward cell [2,0]?

In addition, do I need to wait 4 days after adding more mods for the testing to be effective?

The save should be safe to use without waiting for respawns, Use the readme of the mod you add, if it says wait three more days then just wait for a respawn period to pass. I hope you can get a stable game with the mods you like to use again!

[Problem Resolved]
After a lot of testing I removed Faregyl_Village and Rebuilt patch.
Loaded 5287 - Bendu Olo - The Testing Hall, Level 40, Playing Time 384.49.51.ess
Then I coe to [-1,-1] and walked toward cell [2,0]. No CTDs when I entered the cell! :celebration:
So it wasn't a nuked cell after all.

In TES4Edit Faregyl conflicts with the bgBalancingEVOptionalNPCDiversity, Beautification.esp for 3 NPCs. But, I don't know if that's causing the problem.

Thanks everyone for all your help!