I don't think there is such file with the dictionary you have mentioned about. I've used Google Search and all the related websites only to find out that you need is actually available in the dedicated applications available all over the Internet that are similar to the Daffodil Bengali to Bengali Dictionary.
In the end, you will have to use an application like the one above. Also, most of them allow you to export their database to various documents or you could copy the definitions manually to a text file. A tedious process, but it gets the job done.
