It is standard clause in sale deed to protect buyer in case title is defective 

it is your call whether to agree to such a clause or not 

Ask buyer to delete wordings 

or if the Vendee is deprived of part or whole 
of the said flat, the Vendor shall compensate 
the Vendee the same at all times from their 
personal and other properties

2) if he refuses cancel the agreement and refund earnest money received by you 

• The buyer cannot unilaterally insert a new clause in the sale deed that wasn’t agreed in the sale agreement.

• The added clause—“deprived of part or whole of the flat” with lifetime liability—goes beyond standard indemnity and is unreasonable.

• You can refuse to execute the sale deed unless the clause is revised to match your original terms.

• If the buyer insists, you may cancel the agreement citing breach of mutual terms and non-adherence to agreed conditions.

As per law the vendor has to assure the vendee to compensate the losses he suffers in this regard and it is a general clause  which the vendor cannot refuse, hence  asking the buyer to remove this clause may not be legally valid

The vendor can insist on the buyer to remove the lifetime clause in the deed because this cause is applicable only if the defect in title is observed now and not after 20 or 30 years after purchase. 

Dear Client

The provisions stated above does essentially hold you responsible for lifetime compensation, which is a onerous and unlimited commitment.

Important points:

Indemnity clauses are common for covering the buyer against title defects or legal problems resulting from the vendor's side. This is normal and reasonable.

The expression however making you liable "at all times" and from "personal and other properties" is broad and has the potential to make you liable in the future to any extent, which is not normal or desirable.

As the buyer originally agreed to your conditions but subsequently included this burdensome condition in the sale deed, you have a sound reason to object to execution or even rescind the agreement if the condition was not agreed to by both parties.

You may insist on a limited indemnity clause that protects only against losses arising out of defects in title or contractual breaches and not lifetime or unlimited

It should be mentioned unless the same is not fatal to your title in future 

The  purport of clause mentioned by vendee and vendor is same. You insist on clause proposed by you. There is no such liability of vendor for all time to come till infinity. Vendor is not bound till the end of world, such clause is against public policy.