Settlement

Yes your father  in law can get property back legally.

Act applicable in this situation which is passed by Parliament is 

THE MAINTENANCE AND WELFARE OF PARENTS AND SENIOR CITIZENS ACT, 2007

Important section short listed for this case

3. Act to have overiding effect

The provisions of this Act shall have effect notwithstanding anything inconsistent therewith contained in any enactment other than this Act, or in any instrument having effect by virtue of any enactment other than this Act.

23. Transfer of property to be void in certain circumstances

1. Where any senior citizen who, after the commencement of this Act, has by way of gift or otherwise, his property, subject to the condition that the transferee shall provide the basic amenities and basic physical needs to the transferor and such transferee refuses or fails to provide such amenities and physical needs, the said transfer of property shall be deemed to have been made by fraud or coercion or under undue influence and shall at the option ofthe transferor be declared void by the Tribunal.
2. Where any senior citizen has a right to receive maintenance out of an estate and such estate or part , thereof is transferred, the right to receive maintenance may be enforced against the transferee if the transferee has notice of the right, or if the transfer is gratuitous; but not against the transferee for consideration and without notice of right.
3. If any senior citizen is incapable of enforcing the rights under sub-sections (1) and (2), action may be taken on his behalf by any of the organisation referred to in Explanation to sub-section (1) of section 5.

27. Jurisdiction of civil courts barred

No Civil Court shall have jurisdiction in respect of any matter to which any provision of this Act applies and no injunction shall be granted by any Civil Court in respect of anything which is done or intended to be done by or under this Act.

7. Constitution of Maintenance Tribunal

1. The State Government shall within a period of six months from the date of the commencement of this Act, by notification in the Official Gazette, constitute for each Sub-division one or more Tribunals as may be specified in the notification for the purpose of adjudicating and deciding upon the order for maintenance under section 5.
2. The Tribunal shall be presided over by an officer noi below the rank of Sub-Divisional Officer of a State.
3. Where two or more Tribunals are constituted for any area, the State Government may, by general or special order, regulate the distribution of business among them.

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Matter should be reffered to tribunal constituted under the act

I feel you can give copy(print out )  of this act of gazette notification to senior citizen and after this he should take decission in his legal interest 

https://socialjustice.nic.in/oldageact.php