Can employee of railway avails the benefit of10(26) of assam?

Read: The Supreme Court decision in the case of Lawrence Singh Ingty [1968] 68 ITR 272, is that for the purpose of considering the exemption available under section 10(26), the section would have to be read as if the words ’who is not in the service of the Government’ do not find a place therein. Consequently, Government servants will be entitled to the exemption only if they are otherwise eligible for the exemption. 

sir,

  so whether the employee of railway belong to ST community of Assam can avails the benefit of 10(26)

Yes, provided other conditions of the section are satisfied.

raiwaly accounts section is well aware of conditions, and if the exemption is available, they will issue necessary instructions and certificate to concerned employee.