I'm in the military and looking to buy my parents property with a 'deed of gift'. Are there any implications?

My parents have recently separated and my mother still resides in their jointly owned property. She can no longer afford to live in the property so I have offered to buy the house combined with a small deed of gift from both parents (both have agreed). She has insisted she pays a monthly rent which will be easier to pay than a mortgage. After this (approx 1 year) she would like to move into a smaller property which again I would buy and she would rent. If this were to happen are there any tax issues, Capital Gains or Inheritance which would put a spanner in the works when purchasing both properties? Also are there any other legal implications?