Need Advice

My great grandmother passed 80 acres down to my mom. My mom’s mother, (my great grandmothers daughter) got bent out of shape about it and my mom felt bad so my mom granted her 50% ownership. So they were both equal owners of this property. My mom got sick and was in the hospital for 2 months. While she was in the hospital her mother forged my mom’s signature and had my mom’s name removed from the deed. A few months later when my mom went to pay the property taxes she found out that her name was not on the deed. We have a text message of her mom admitting to “writing her name on the deed”. We can also get proof that my mom was in the hospital at the time. I was my mom’s power of attorney while she was in the hospital. Not her mom.

What is the next step that we should take? My mom gave her a chance before we decided to legally take action but she was not willing to retract what she did. How is this entire process going to go?