Would greatly depend if it’s a cash purchase or if you have your own purchasing closing closets on a loan.

There is a simple way of take 2 of the beds on the top floor, and combining the two of them to make a master suite with a full walk in closet and a master bath. 

Typically we get rid of the closet off the 1/2 bath  - a complete no brainer.

There were 4 beds but the 4th room was converted to make the master & 2 walk in-closets larger, could be changed back.

The 2 best improvements we made were flipping a coat closet originally facing the living room 180 degrees to face the kitchen to be used as a pantry, and the installation of a center island and range which allowed us to add a dish washer that previously did not exist in the kitchen.

If you're that worried get a portable alarm system. 

Make sure every bedroom has sufficient square feet, closets and fire egress offering two escape routes (window outside and door).As far as appraisal, odds are good that the modifications will reduce value.

He's right, newer is usually better.20s, you'll have knob and tube wiring, fuse box, often 60 to 100 amp service, iron pipe for water lines, lath and plaster walls, wood work, fixtures and hardware that will be difficult to replace or duplicate, small closets with single doors, often you'll have stone foundations, odd size windows and smaller rooms.

Remove closets or electric sockets so it does not meet the requirements of a 2 bedroom.

Remember sellers always keep certain hidden costs in the closet.