trying to buy a house for my parents

I am a sixteen yrs. old boy with autism I have this problem my parents have been renting the house we are living in for the last 10 years. We have never missed a payment always payed the rent on time but now our land lord is getting on in yrs and wants to sell the house and we are not going to be able to stay here any more my dad was diagnosed with stage 3 cancer and is going to be starting kemo soon and my mum is the main carer of me and my dad so she can not work because she has to be at home what I would like to do is keep the house we are in by buying for my parents to show them I am grateful for all they have done for me and my sister and let my father live what ever life he has got left in the home. hope you can help me make this happen