You can ask her (in your mind) to visit you in your dreams, or you can try automatic writing. Automatic writing is when you take a pen/pencil and paper and just write what comes to you. It helps if you have a quiet space to be in and you meditate a little beforehand.
Reference: https://www.quora.com/My-grandmother-recently-passed-away-Is-there-any-way-to-safely-contact-her
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