mother-in-law's /mothers-in-law's Possessive

https://forum.wordreference.com/threads/mothers-in-law-possessive-form.3917112/#js-post-20048821

Friendship is abstract or concrete Noun

https://www.vedantu.com/question-answer/pick-out-any-concrete-and-abstract-noun-from-the-class-10-english-cbse-5f491300eeae724665abac0a