Extracting a specific string after a given string from HTML file using a bash script

I can't sensibly advise doing this, because parsing html with regex is not likely to end well but you might be able to get the string MANIKA with

sed -nr '/MOM:/ s/.*MOM:([^"]+).*/\1/p' file

It works OK on your sample anyway...

Notes

• -n don't print anything until we ask for it
• -r use ERE
• /string/ find lines with string
• s/old/new/ replace old with new
• .* any number of any characters
• ([^"]+) save some characters that are not "
• \1 backreference to saved characters
• p print just the lines we changed

grep -Po 'MOM:\K[^"]+' file.html

Warning: this is not a very robust solution; And your HTML is not valid