a) Yes you can sell the villa as your mother is the owner of 161square yards and the remaining 95 square yards was in your father's name and after his demise you have the legal heir certificate wherein the names and relationship of all legal heirs are mentioned in the certificate.
b) For effecting a sale of villa, you will need the original sale deed belonging your father and mother, death certificate of your father and the legal heir certificate.
c) Now coming to effecting a sale to a third person, in the said sale deed, Your mother will need to sign as an independent owner for 161 square yards and for the remaining 95 square yards, all of the legal heirs(your mother included) will sign as legal heirs of your father .
d) No other formalities are required to be completed.
e) for your information succession certificate is for only movable properties & bank deposits and not applicable for immovable properties.
Hopefully all of the legal heirs are aged above 18 years.
Hope this helps.