Hi Lakshmi,
I'm no qualified legal advisor, just sharing my experiences / knowledge. The Power of Attorney is a very powerful document in the wrong hands -- we had a very very bitter experience

& now all relations with my husband's siblings are totally cut off !! So better be extra careful, rather than being tormented for life.
In such matters better to rule with the head , not the heart , however close / loving/ trustworthy the person may be.
Has it been mentioned by your husband that the P of A will be 'exclusively' for the construction purposes -- there are many types of P of A , esp. general ones with no specified time limit is the worst trap to get into ! Has the house been constructed now -- whose name is the property deed registered in ?? Surely you would've had some legal consultation done before handing over the Power of A to her -- that same consultant can advise you now ?
Just last year we sold a house of ours, by giving a P of A to the buyer itself, because we just couldn't travel to India during that period. But we made sure to include all the clauses with respect to time frame, purpose of the P of A was elaborately specified
including what the buyer cannot use the document for . After our experience, a cousin brother of mine has refused to give P of A even to his own Father !!!! and insisted on coming down from USA, just for 2 1/2 days to sign & finalise a land purchase ........
So check out with your hubby / lawyer etc. If you need any more details I can ask my hubby.
Regards.