your wife was the co-owner of the flat
upon her demise her share in the flat will devolve on her legal heirs as per intestate succession
the legal heirs of a Hindu female are her widower [husband] and children
thus such legal heirs will inherit the share of the deceased wife equally
there is no concept of survivorship i.e. automatic devolution of share of deceased co-owner to the name of the surviving co-owner
survivorship would come into play in the case of HUF property [even that has been now done away with by the Hindu Succession Act]
your daughter has inherited a share in her late mother's share alongwith you
so your daughter has become a co-owner having an undivided share in the flat
however for proper conferment of title on her as well as the transfer of your share in your name from out of your wife's 50% share in the flat, a letter of administration will have to be applied for from the Court