In this gameset, you will see how this Blanka can stop Bison's Psycho Crusher (Flying Fire Screw Flash)
You will need Fightcade to see the gameset between these two fighters.
The simple is answer is you need to hit the low kick
How to stop Psycho Crusher Bison with Blanka in Street Fighter II Champion Edition sfce FightCade
Here is the link to the game set of Blanka VS M. Bison in Street Fighter 2 Champion Edition
Wait for it!
Hope that helps.