148 Notice binding on legal heirs ?

I think yes,

Legal heirs are responsible to inform department about death and respond on requirements asked in notice

but is not mandatory to inform the same to department.

It is mandatory and responsibility of person receiving notice to inform department

actually, notice of 148 required to be issued within time limit i.e. on or before 31.3.2018 on the legal heirs. but in this case, notice to such deceased person. how legal heirs will proceed for the same without issuing fresh notice within time limit on them ?

Just write a letter to department specifying death of assessee and xyz being legal heir thereafter department will proceed and send notice accordingly

but.... in that case notice will be time barred. its cannot issued after 31.3.2018

Still its Assessees or Legal heirs responsibility to inform department when they realise their mistake simple

reference to the case ITO vs Sikander Lal Jain
if the notice is issued in the name of dead person, but served on all the legal heirs, the notice cannot be regarded to be invalid one. 

How could department come to know about the demise of the assessee until the same has been informed. But after the reciept of the notice the department would pursue the case with the legal heir/s in a similar way as it would have been pursuing with the assessee. If at the end some tax demand comes out then the legal heir/s will be responsible to pay the same to the extent they have been benefitted in the capacity of the legal heir/s of the deceased.

Abhay Gupta sir. you rightly said. but in this case notice of 148 issued in the name of demise person. if they want to issue notice in name of legal heirs, its required to be issue within time limit i.e. on or before 31.3.2018. hence, I think notice is barred by limitation.