1) Your mother must certainly lodge a police complaint and possibly make it an FIR for criminal intimidation and threat.
2) Your neighbour cannot hide behind the illegality of construction of the car porch to justify his illegal construction of the wall depriving you of light and air at such proximity.
3) What your neighbour has done is legally an infringement on your easement rights. Let me quote for your benefit what easement rights is defined as"Easement" defined. -An easement is a right which the owner or occupier of certain land possesses, as such, for the beneficial enjoyment of that land, to do and continue to do something, or to prevent and continue to prevent something being done, in or upon, or in respect of, certain other land not his own. Dominant and servient heritages and owners. -The land for the beneficial enjoyment of which the right exists is called the dominant heritage, and the owner or occupier thereof the dominant owner; the land on which the liability is imposed is called the servient heritage, and the owner or occupier thereof the servient owner. Explanation. -In the first and second clauses of this section, the expression "land" includes also things permanently attached to the earth; the expression "beneficial enjoyment" includes also possible convenience, remote advantage, and even a mere amenity; and the expression "to do something" includes removal and appropriation by the dominant owner, for the beneficial enjoyment of the dominant heritage, of any part of the soil of the servient heritage, or anything growing or subsisting thereon. Illustrations
(a) A, as the owner of a certain house, has a right of way thither over his neighbour B's land for purposes connected with the beneficial enjoyment of the house. This is an easement.
(b) A, as the owner of a certain house, has the right to go on his neighbour B 's land, and to take water for the purposes of his household, out of a spring therein. This is an easement.
(c) A, as the owner of a certain house, has the right to conduct water from B 's stream to supply the fountains in the garden attached to the house. This is an easement.
(d) A, as the owner of a certain house and farm, has the right to graze a certain number of his own cattle on B 's field, or to take, for the purpose of being used in the house, by himself, his family, guests, lodgers and servants, water or fish out of C 's tank, or timber out of D 's wood, or to use, for the purpose of manuring his land, the leaves which have fallen from the trees in E 's land. These are easements.
(e) A dedicates to the public the right to occupy the surface of certain land for the purpose of passing and re-passing. This right is not an easement.
(f) A is bound to cleanse a water course running through his land and keep it free from obstruction for the benefit of B, a lower riparian owner. This is not an easement."
4) Therefore your legal remedy is to approach a civil court to file a suit to compel the neighbour to pull down the wall or partially demolish it to the extend of allowing you sufficient light and air.
5) You need to think of alerting the car porch or any Demolition only if and when you are required to do so in case your neighbour complains or you receive a notice. Their of no direct linkage between this and the illegal wall he had erected.
6) Engage a lawyer to assist you locally.