Capital gains tax

Since, your mother has deposited the capital gains amount in capital gains account scheme with in time, as of now there's no compulsion to invest the same in new property immediately. however, the capital gains amount required to be invested by way of purchase, within 2 years i e. 30/08/2020 or by way of construction, within 3 years i e. 30/08/2021, from the date of sale of original asset i e 30/08/2018, in a new house property to avail the deduction under section 54 else the same will be treated as long term capital gain for the assessment year 2022-23