My mother has dementia and at present is home but under Hospice Care. She has always been a devote Catholic. Is this a sign?

When my grandmother was in her mid 90's she had hardening of the arteries and would sometime just blurt out a nursery rhyme from her childhood (in her first language, Italian). Your mom is getting comfort from the Lord through prayer, and I'm not surprised she's reverted to her native German since dementia tends to do less damage to your long-term memory (i.e. childhood memories). I don't know if I would attempt to interpret what it means. Praying with her and singing to her or playing soft, music from her religious tradition and generation may also comfort her. May you both receive peace in your hearts!