What is the Limit for record retrieve in a Salesforce subquery ?

This point can help you understand this:

In a SOQL query with parent-child relationship subqueries, each parent-child relationship counts as an extra query. These types of queries have a limit of three times the number for top-level queries. The row counts from these relationship queries contribute to the row counts of the overall code execution.

So, Total number of records retrieved by SOQL queries would be 50,000 altogether.