Pawan, your latest query is not clear. If your company's policy does not cover distance after a certain limit, then you need to stick to the same. I am sure the employee joined your organization knowing this detail, and you informed him of the same. If he knew it, then he can't morally ask for any other reimbursement as they are not part of his employment. Making such exceptions is unfair to other employees.
Company Policy on Reimbursement
Now, my reply to the more idealistic replies as to whether the company should make an exception: in that case, there cannot be a limit to it. In a perfect, Utopian world, it might be possible. But in this case, there is no need to do the same.
Alternative Solutions
As a side note, as a retaining policy, you can give him a special allowance to meet travel expenses. It can be a fixed amount and not on actuals. But the resulting increase in CTC and financial burden has to be considered.
Regards.