gift

yes u can take gift of Rs. 100000/- from ur mother.... in case of specified relatives (which also includes mother) any amount of gift can be received and it will be totally exempted.....

and second topic ..... flat is in the name of both u and ur father.... show the flat as a fixed assets in both ur and ur father's balance sheet but total value cann't exceed total cost of flat.... whole amt. is paid by you ... you may show it in ur books as unsecured loan to ur father.... and receive it in future years in cash....

You can accept this gift and it totally exempt from income tax but you should prepare gift deed duly signed both of you and it should be witnessed in a proper manner.