How do I get my mom to agree to let me help around her house when I visit?

I am the baby of 5 children, I am 51 yrs of age and my mother will NOT let me do anything to help when I go to visit her. She is 87 yrs old and getting very mean,snappy, etc. I want to contribute to helping her an I live in Ky she lives in IN. I recently visited her and I could Not even go grocery shopping for her,usually my brother does this usually weekly but i wanted to give him a break from all of the chores. My mom through fits of me touching anything yelled at me and is still mad at me now that I am back in Ky. How do i show my mom that I love her?? It is killing me to see everyone do their part but me....please I need some help here and don't know what to do !! Thank you Patty