Translation:Mi madre me ama mucho.
In this case mucho modifies the verb 'love' making it an adverb. When used as an adverb, always use mucho. When used as an adjective, mucho will change to match the gender and number of the noun it modifies.
Mucho dinero , muchos gatos, muchas niñas.
In a previous sentence in level one, the sentence read, "Mi papá me quire muy mucho." I thought, "aHa! I won't get it wrong this time, and all I did was change the subject. Now it's STILL wrong. This time the verb "ama" is used, and the adverb "muy" is missing, What gives?
Quire (querer) and ama (amar) both refer to love. Mucho = a lot. Muy mucho = very much.
Your sentence should be correct (assuming you typed 'quiere', not 'quire'). Next time hit the report button. Often Duo is focusing on particular words, in this case "amar" and doesn't really acknowledge alternate correct sentences. Reporting it helps Duo add alternate choices.
I usually don't have the confidence to wag a finger at Duo. Someday, I will, and if the sentence comes up again, I will, indeed, do it, Laz. Thanks for the help. (Come to think of it, I may have misspelled "quiere"...maybe that's what triggered the flag?)
7/16/18 -- FYI - Duo does accept 'Mi madre me quiere mucho' (though not 'muy mucho').
"Muy mucho" is not used.
It is both awkward and useless because there is "muchísimo" that means exactly the same thing.