If under Will property is in my name can it be challenged later

My mother & I share a common property which she has willed to me after her death. However, I believe it can still be challenged after her death, unless, her share is gifted to me while she is alive. As there is a really strong chance that it could be disputed after she is no more, she is very keen to gift it to me while she is alive. She is 87 years old and in very poor and fragile health .... cannot be going to registrar's offices etc. Is there any way that the gifting can be done at home? I am the first holder in the flat and she is second.