My answer is "ng". Although, both may be correct, the use of NG on both sentences sounds more conversational than using ANG. (if that's what you're trying to achieve also) it would sound weird to me using the ANG on those sentences.
* And if what you posted are the english translation of the sentences, I think there's the need to put in the term "lang" to state that the action just took place earlier/just ended. I myself would not be able to understand that the action just ended if that "lang" term wasn't added on the sentence.
*Kasasara "lang" ni John ng bintana
*Kalilinis "lang" ni Luis ng kusina
These sentences to me, sound more conversational po.
I hope that helps po. ๐