Mother love or mother's love?

Solution 1:

I believe that this can be classified as an attempt at solecism, or, in a nutshell, intentionally mucking up grammatical conventions to make a point. The view the author holds is that no religion or belief can claim to have influenced the love a mother has for her child... it's simply mother love. The author is using "mother love" as a term to distinguish it from "Christian love" or "Buddhist love", because he or she believes that external claims to a mother's love for her child are erroneous.

Solution 2:

...it is mother love." Is it possible to express "mother love" as it is? Shouldn't the word 'mother' be subjected to Possessive case and make it "mother's" love? Or is it just a proofing error?

It is not a mistake, actually it is the correct form:

the Saxon genitive, as you say, is used to express the 'possevive case', that means that 'the person possesses something', in this case it would mean 'that belongs to a mother'.

In the case you quote the 'love' does not belong to the mother, but 'flows' from the mother to her child.

Therefore the form you consider correct is actually improper, "mother" here has the function of an adjective, corresponding and substituting "maternal love" = "love relating/peculiar to a mother"

Solution 3:

No, because "The love of a mother is a mother's love" is tautological, i.e. an empty assertion, while "The love of a mother is mother love" is not empty, so "a mother's love" and "mother love" can't mean the same. (I supplied the "a" in "a mother's love, because without the "a", I find the sentence ungrammatical.)

Grammatically, "mother love" is noun, specifically a compound noun, composed of the two nouns "mother" and "love". But "a mother's love" is a noun phrase (NP), and is equivalent to "the love of a mother".

One way to tell the difference is that "love" in the first cannot be modified by an adjective (because neither part of a noun-noun compound can be modified by an adjective), but "love" in the second can be. *"mother eternal love" is ungrammatical, while "a mother's eternal love" is grammatical, and means "the eternal love of a mother". ("eternal mother love" is simply the adjective "eternal" modifying the compound noun "mother love".)

Solution 4:

The traditional expression is "a mother's love".

The writer probably wrote "mother love" because English wasn't their first language, and they just decided to use "mother" to describe this unique and well-known form of love.

Since the meaning's clear, I'd let them off the hook and afford them a bit of creative license.

As for "mother" not being an adjective—well, of course it can be one, as in "the mother ship".