The first person I turn to is always my mother, who offers me a friendly ear and is always be my ally.

There are other variations that you can use.

I used "is always my ally" because the rest of the sentence is in present tense.
- The first person I __turn__ to __is__
- __offers__

She has experienced a lot of good and bad, so she gives me sound advises.ce

But I think it's about time to leave from my mother because I'm an adult.

The first person I turn to is always my mother, who offers me a friendly ear and will always be my ally.

She has experienced a lot of good and bad, so she gives me sound advisesce.

"advises" is the habitual form of the verb "advise"

"advice" is the noun. It's considered uncountable, so doesn't have a separate plural form.

But I think it's about time to leave frommove on from relying on my mother because I'm an adult.

You need a little more here to make this sentence sound complete.

"cause" as a replacement for "because" is _very_ casual, and when it does show up in writing it's often written " cos' " if you want to be that casual. In writing it's much more normal to just use because.

The first person I turn to is always my mother, who offers me a friendly ear and is always be my ally.

She has experienced a lot of good and bad, so she gives me sound advisesce.

"advise" is a verb (so, "She advises me"). "advice" is a non-count noun, so it cannot be pluralized.

But I think it's about time to leave from my mother because I'm an adult.

"cause" (often shortened to "cuz" in text and spoken speech) is mostly spoken, while "because" is more preferred in writing

The first person I turn to is always my mother, who offers me a friendly ear and has always been my ally.

She has experienced a lot of good and bad, so she gives me sound advisesce.

But I think it's about time to leave from my mother cause I'm an adult.

But I think it's about time I became less dependent on my mother now that I'm an adult.

The first person I turn to is always my mother, who offers me a friendly ear and is always be my ally.

You can also say these:
1.) "[...] and will always be my ally."
2.) "[...] will always be on my side."
3) "[...] is always on my side."

She has experienced a lot of good and bad, so she gives me sound advisesce.

But I think it's about time to leavedistance myself from my mother 'cause (or because) I'm an adult.

Maybe "because" would be better here because the sentence has a formal tone, so it would match better.

The first person I turn to is always my mother, who offers me a friendly ear and is always be my ally.

She has experienced a lot of good and bad, so she gives me sound advisesce.

But I think it's about time to leave from my mother because I'm an adult.

The first person I turn to is always my mother, who offers me a friendly ear and is always be my ally.

She has experienced a lot of good and bad, so she gives me sound advises.

But I think it's about time to leave fromnot be dependent on my mother cause I'm an adult.

"... time to leave..." would be you want to leave your mother and perhaps not have a relationship with her. But, I am assuming you wanted to say that you don't want to dependent on her too much.