^^ You're right. I'm pretty sure I've read it here that Seochill's mother passes away. Her last duty or whatever was convincing Hanam's mother to agree to the marriage. I don't remember if she made it to the wedding though.
I hope this is allowed, but here's the link to read the detailed spoilers for the last episode:
You need to scroll to Post #76 and click the link that says "click here to reveal" in it.
I watched every episode except the last!!!! I'm so mad at myself! So after you've watched the last episode, please post okay?! Roughly I can guess how the show ends but I just want confirmation for peace of mind