In this trick we're gonna see how a webform could be added as the block.
Well if you got stuct over it and scratching your head over this for so long, dont worry it is very easy solution,
Just head over to the Webform's advanced settings as shown below,
And then check "Available as block" checkbox. Refer below image for the same,
After this hit "Save Configuration" and save the settings.
After this you will find your webform in Structure->Blocks, starting its name with webform.
Hope this helped you, please let me know your concerns in comment section below.
Cheers!! :) ;)