I spoke at my mother's memorial service. I did cry. I did stop for a few moments mid-speaking but continued on after I found my voice again. As others have said, absolutely no one will think any less of you or even consider it a negative aspect of your overall presentation if you do breakdown at what is possibly the most understandable place in a person's life for them to break down crying. Some might even be all the more affected by what you are saying if it is punctuated by well-deserved tears or sobs. So I would say, first of all, don't worry too much about it, and if it happens, let it.

But beyond that, for more practical advice, you can just stop for a moment to compose yourself. Take a few slow breaths, close your eyes if it helps to ground you, feel your feet on the floor.

Another thing that can be grounding is if you have someone in the audience you are really very close to. Talk to them before hand and tell them that you're concerned about losing your composure and not being able to finish speaking. When you're up there speaking, if you feel yourself starting to lose your composure, look at them, make eye contact. They can give you a comforting smile and nod, giving you the reassurance you need and help to further ground you. They will know ahead of time, since you will have asked them to be your support when you're up there in front of the audience. Meet their eyes, remember that they're there for you. Can even ask that they give a gesture of acknowledgement and comfort like putting their hand over their heart. In my experience, having that one person as prepared support out there can make a big difference in one's immediate sense of confidence.

I wish you well in your speech and I offer my sincere condolences. Losing your mom can be among the most painful experiences in a person's life. Having already lost your dad you no doubt already know that, but either way, don't forget to be kind to yourself and take care of yourself.