Step 1: Understanding Class I heirs.
As per Hindu Succession Act, Class I heirs include son, daughter, widow, mother, etc.
Step 2: Exclusion of father.
Father is a Class II heir, not Class I. He inherits only in the absence of Class I heirs.
Step 3: Analysis of options.
- Son: Class I heir.
- Widow: Class I heir.
- Father: Class II heir.
- Mother: Class I heir.
Step 4: Conclusion.
Hence, the correct answer is (C) Father.