The best option if your mother gave you the laptop and she does not know the password to her Microsoft account would be to reset Windows and choose to delete everything to make that laptop your own, then add the details of your own Microsoft account to the new user that would be created after the reset.
Please note, this process is like clean installing Windows and all apps and data will be deleted from the laptop.
Click the power icon on the Login screen.
Press the Shift Key and click Restart,
Your laptop will boot into the Windows Recovery Environment
Go to Troubleshoot - Advanced Options - Reset this PC
Choose to keep nothing.
Then start the Reset.