Will Medicare pay for a ramp into our home?

My 91 year-old mother has lived with me for five years. Her health is generally good, meaning no cancers or diabetes or such. She has had Parkinson's Disease for a very long time and now must use a walker or wheelchair. She cannot walk unassisted and her balance is almost nonexistent. We now need at least one ramp for her to get in and out of the house safely. Does Medicare assist with that expense?