I absolutely loathed my mother asking me about my menstrual cycle.
I was fine asking for the products I needed, fine with recording it myself, didn't have hygiene problems but my mother would ask if 'I was on', and if she found out, would record it on the calendar. She was helpful in leaving the scented 'nappy sacks' in the bathroom for sanitary products, and showing me what to do with them, which I appreciated.
She wasn't doing anything wrong per se, but at that age, I just desperately wanted some right to privacy regarding my body, that is, not having to tell other people when I had period. I didn't think it was much to ask that something about my body was just kept private and to myself.
I can't speak for anyone else, if they ever felt like this, but I really, really hated it. It felt intrusive - and I told her as much as well, but I had no issue with stating my opinions - a more shy lass might.
That being said, it is very important she isn't leaving dirty sanitary products around. Sometimes it rights itself but sometimes it really doesn't. I've known grown women who still didn't know not to flush tampons down the toilet, and have caused a blockage in their partners parents house as a result! Also know of one case where an adult woman frequently 'forgot' to bin her sanitary towels. They weren't even wrapped up, just left open for her partner to find (before anyone even goes there, I'd find it gross myself coming across this, periods aren't gross but used sanitary products can be!). Unfortunately, by then, it was a well ingrained habit that it didn't matter how much she was spoken to about it, would continue.
Getting the balance right can be difficult between making sure she has all the information she needs, is being hygienic for herself and those around her, but not being too invasive!