Try downloading and running the delta patch for MSRT from the the Update Catalog.

https://www.catalog.update.microsoft.com/Search.aspx?q=KB890830

Select the x64 for Windows 7 (second on list) Download and you will be presented with two files (select bottom file).

Patch file (~6.77 MB): windows-kb890830-x64v5.77delta_acd7b02e03c86f374a14271a7b0844a3e4ad64dc.exe

Note: See EDIT at bottom of this post.

Save file then double click to install. It should update the version of mrt.exe on your machine to 5.77.16547.2. If successful the Malicious Software removal Tool should appear. Do the default Quick Scan then reboot computer and check Windows Updates again.

Hope this helps.

~bhringer

EDIT: For ease of access, below are direct download links for the appropriate 32 and 64-bit versions,

32-bitwindows-kb890830-v5.77-delta_a9f4bcd60fdf765b24ed4b3c30af93a31d3517d4.exe

http://download.windowsupdate.com/c/msdownload/update/software/uprl/2019/11/windows-kb890830-v5.77-delta_a9f4bcd60fdf765b24ed4b3c30af93a31d3517d4.exe

64-bit

windows-kb890830-x64-v5.77-delta_acd7b02e03c86f374a14271a7b0844a3e4ad64dc.exe

http://download.windowsupdate.com/c/msdownload/update/software/uprl/2019/11/windows-kb890830-x64-v5.77-delta_acd7b02e03c86f374a14271a7b0844a3e4ad64dc.exe

How do I now If I have 32 or 64 bit?

Select the Start button, right-click Computer, and then select Properties.

Under System, see the system type.

https://support.microsoft.com/en-us/help/15056/windows-32-64-bit-faq