Need help in putting the single quote and constant timestamp in plsql
To add single quotes in a string literal, just double it, or use the chr function.

E.g. 'hello '' world' represents the string hello ' world. 'hello '||char(39)||' world' is the same. '''' is a string literal representing a single single-quote.

To get your fixed end time, just concatenate it.

select ''''||to_date(:From_date,'dd-mon-yyyy')||'''' from Scehma.table1;
select ''''||to_date(:To_date,  'dd-mon-yyyy')||' 23:59:59''' from Scehma.table1;