Yikes!  Sunday is Mother's Day and aside from a card, you want to show mom you really care.  It is the MOST popular restaurant night.  How about a few other ideas?

Flowers (never a bad move)
See if there's a few chores you can help with
Gift cards for stuff like groceries or gas
Things she uses for a special hobby
Time - yup, spending time with mom is the greatest gift of all.  She'll agree to that.

Happy Mother's Day!