Cannot install windows update KB4074598

If you used SevenForums Rename SoftwareDistribution folder bat by Shawn Brink, you will have your original as SoftwareDistribution.old saved in the same location as SoftwareDistribution.

To the best of my knowledge, Security Monthly & Quality Roll-ups are cumulative, i.e. each Monthly Rollup contains the previous Roll-ups plus additions.
Have you tried offline installer? If not, here's the link to M$ KB4074598 you want 2018-02 Security Monthly Quality Rollup for Windows 7 for x86-based Systems (KB4074598) and link for M$ KB4088881 you want2018-03 Preview of Monthly Quality Rollup for Windows 7 for x86-based Systems (KB4088881).

If you receive an error, please post error code.

Referencing your post #21
Here is my post#18 in pertinent part, download and run UltraVirusKiller
Click on System Repair. In Find a Fix/app search box type Fix & enable Window Update
either check checkbox and click Run selected app or double-left click Fix & enable Window Update & click Yes.
UVK by Carifred has a plethora of tools in his UVK suite.

If you still receive error message, you can also try installing offline update is safe mode. To enable safe mode:

1. Immediately after the computer is powered on or restarted (usually after you hear your computer beep), tap the F8 key in 1 second intervals. May be different F key on your computer.
2. Use the arrow keys to select Safe Mode and press ENTER. For more information about Safe Mode options, click here for Windows Vista/Windows 7.
3. Try installing updates.

Did you download the KBs from M$ and run them, (Stand Alone Installers)?

Download and run Reset_Reregister_Windows_Update_Components.bat

Try Stand Alone Installers again!

Didn't work again? please zip and post WindowsUpdate.log
File located: C:\Windows

Here's the error codes for your failing updates:

Handler FATAL: CBS called Error with 0x800f081f
Handler FATAL: CBS called Error with 0x80070002
Need to take a look at your CBS.log too!

Location: C:\Windows\Logs\CBS don't need the persist logs
zip/compress log if it's too large to post.

In the meanwhile, you can try running, FYI copy/paste into CMD
chkdsk %SYSTEMDRIVE% /R
from an elevated command prompt, (right click cmd, choose run as administrator) answering the question with "Y", rebooting your machine to let chkdsk run, and then trying again.

Appears to be component hive corruption. SURT tool didn't pick up error.