Source: 100 and Healthy https://www.youtube.com/watch?v=mb--QxUnEv0&t=1338s The speaker is Dr. Oliverira.
Rosane Oliveira, DVM, PhD, is Founding Director of Integrative Medicine at the University of California Davis School of Medicine with over 20 years of experience as a molecular geneticist and has a special interest in nutritional genetics and genomics
This condition is called Essential Tremors, and it is one of the impacts of increased mTOR and IGF-1 levels that so many of us have from eating too much meat. According to Dr. Oliverirea, as an example, in her presentation she showed that eating 1.5 ounces of chicken per day, increases your chances of getting Essential Tremors by x21!! Wow. Eating meat and diary in excess has consequences and there's a lot of research to back that up.
Unfortunately, it maybe to late for your mother. But, this is for all the other mothers and fathers out there.