Hope you are doing well.
Please accept our sincerely apology for delay over the issue.
Please use below command to get the expected output for your query.
You should use one extra quotes for your query as the data in hdfs saved as "A" so to retrieved the data you should use one extra quote.
Please refer below command
select * from loandata1 where grade = '"A"';
Please refer below screen shot
Hope it resolves your query.
If you have any further query,please let us know.