Yes, but you might want to add お before those words when referring to other people's. For example, あなたのお母さん (your mother). It sounds a bit unnatural without the お.

Yep. ~さん always refers to someone other than the speaker.

今日は、君が 僕の答えを 最も良い答えのように 選ばたのを どうも 有難う御座居ます。それでは、僕は他のメムバーの質問を答えることに 良い肯定が あります。私達と一緒に 外国語を習って続けることを 願います。良い 一日を。　/　Hi, thank you very much for having chosen my answer as the best one.　This gives me a positive recognition when I answer the questions of other members.　I hope that together we continue the learning of foreign languages.　Good day.

Thank you all for your help :)

The honorific form of「母(はは)、父(ちち)、姉(あね)、兄(あに)」are「お母(かあ)さん、お父(とう)さん、お姉(ねえ)さん、お兄(にい)さん」, respectively. The general practice is as follows: 1) In a place where you are with someone else [the outsiders] (such as your friends, classmates, colleagues) and their family members: You always have to address them using the honorific form when you refer to their mother, father, elder sisters or elder brothers, e.g., 友達のお ... さん. 2) In a place where there are no outsiders, i.e., solely with your family members: In this case, you are supposed to address your mother, father, elder sisters or elder brothers using the honorific form, e.g., お母さん、お電話。= "Mum, it's your (tele)phone". 3) In a place where you and your family members are with the outsiders: You should not use the honorific form when you try to refer to your mother, father, elder sisters or elder brothers, especially when you are going to introduce them to the outsiders. You are only allowed to say something like, こちらは 私の 母 / 父 / 姉 / 兄 です。 I hope that the situation becomes clearer regarding the use of honorific form in different situations. --- Good weekend. / 良い 週末を。