Former AP here. Maybe she didn't think about getting a card or gift this year, it doesn't mean she doesn't care about you
It was very nice from her to do so last year.
That being said, I would have never said "Happy Mother's Day" to my host mom when I was an AP. Not because I didn't care (I liked her) but because ... she is not my mom.
Now that my mom has passed away, I call up my grandma and wish her a happy mother's day and she is touched by it.
Please don't make a big deal out of your AP not doing anything this year. Have a little talk with her to see if she's happy these days and don't bring up the topic about mother's day. Maybe she just misses her mom and wanted to think about something else ...
Have a great day!