The renal failure is likely a combination of the underlying diseases viz multiple myeloma, diabetes and hypertension. You do not mention any previous creatinine level but if this was normal a year ago then the renal failure is most likely almost exclusively due to the multiple myeloma.
Multiple myeloma is a kind of cancer of the plasma cells in the bone marrow. This disease has to be staged. There are several factors which go into the staging of multiple myeloma. A markedly elevated B2 microglobulin speaks of a worse prognosis than if the level was normal. However, as with everything in medicine, one must put the entire picture in context and see what some of the other prognostic marker levels are and what stage of multiple myeloma your father has. Life expectancy is estimated at a few months in patients with advanced disease or it can be 5 years in 50% of patients. Once the disease has been staged and the response to treatment ascertained only then can one give a better indication of life expectancy.
You mention that your fathers weight is 47 kg. This is a matter of concern. He should be evaluated for any additional underlying condition that might be responsible for this.