If you arent a mom, dont expect a gift on MOTHER'S DAY

And, shes not your mother/grandmother. Whoever grounded you is stupid.

I'm guessing that your mother wanted her sister (or sister-in-law) to have something out of pity for her being alone. Did she ask you to get her something ahead of time? Or did she just ground you for not thinking of doing it?

Suddenly giving gifts is an obligation?

Me, too. She was a great aunt and like a second grandmother. She always got a card and gift and is greatly missed. Sounds like OP might not be close to said aunt, though.

Keep in mind the Mother's Day has become another one of those holidays where everyone is special. They don't even have to have kids. And if you point that out, you instantly get hated because, WAH, it means you're putting too much pressure on women to have kids so they get special attention. Personally, you should appreciate the woman or women who have raised and taken care of you every day rather than just one assigned day of the year. Don't feel guilty for not sending her a gift, she's not a mother. She wants special recognition for the daunting task that is raising a child, she should have one.

When my nephews were little they would send me a card I mothers day even though I don't have kids. When I said they didn't need to do that, my sister who is a single parent,said that I did more for the boys than their father did, so they wanted to show their appreciation.

Wtf she's not your mom

some aunts always see their nieces and nephews like their own kids... some of those aunts want some loving in return too

It is common in other countries to celebrate other people than just your own mother on Mother's Day? Seems weird to me.