If a question has 2 answers and I can only see one , does that mean the other person who answered, has blocked me ?

it could mean one of a few different things: they could have deleted their answer, the author of the post may have deleted their answer, they could be someone you have blocked, they could be someone who blocked you, or it could be somebody who is filtered out, if you filter content from a certain age group, or if you filter adult content.